STC11F/10Fxx Series MCU STC11L/10Lxx Series MCU Data Sheet

STC11F/10Fxx series MCU
STC11L/10Lxx series MCU

Data Sheet
STC MCU Limited 1

Content
Chapter 1. Introduction......................................................................3
1.1 Features................................................................................................. 3
1.2 Block diagram....................................................................................... 4
1.3 Pin Configurations . ............................................................................. 5
1.4 Pin Descriptions.................................................................................... 6
1.5 Pin Drawings......................................................................................... 7
Chapter 2. CLOCK, POWER MANAGENMENT, RESET........10
2.1 Clock Network ................................................................................... 10
2.2 Power Management ........................................................................... 11
2.2.1 Idle Mode......................................................................................................11
2.2.2 Slow Down Mode.........................................................................................11
t ed
2.2.3 Power Down (PD) Mode.............................................................................12
imi
2.3 RESET Control.................................................................................... 12
L
2.3.1 Reset pin.......................................................................................................12
2.3.2 Power-On Reset (POR)...............................................................................12
U
2.3.3 Watch-Dog-Timer........................................................................................12
C
2.3.4 Software RESET..........................................................................................13
M
2.3.5 MAX810 power-on-reset delay...................................................................13
Chapter 3. Memory Organization...................................................14
C
3.1 Program Flash Memory...................................................................... 14
S T
3.2 Data Memory........................................................................................ 15
3.2.1 On-chip Scratch-Pad RAM........................................................................15
3.2.2 Auxiliary RAM............................................................................................15
3.2.3 External RAM..............................................................................................15
3.2.4 Special Function Register for RAM...........................................................15
Chapter 4. Configurable I/O Ports..................................................20
4.1 I/O Port Configurations...................................................................... 20
4.1.1 Quasi-bidirectional I/O...............................................................................20
4.1.2 Push-pull Output.........................................................................................21
4.1.3 Input-only Mode..........................................................................................21
4.1.4 Open-drain Output......................................................................................21
4.2 I/O Port Registers .............................................................................. 22
Chapter 5 Instruction System..........................................................24
5.1 Special Function Registers.................................................................. 24
5.2 Addressing Modes.............................................................................. 28
5.3 Instruction Set Summary.................................................................. 29
2
Chapter 6. Interrupt.........................................................................33
6.1 Interrupt Structure.............................................................................. 34
6.2 Interrupt Register................................................................................ 35
6.3 Interrupt Priorities............................................................................ 37
6.4 How Interrupts Are Handled............................................................. 37
6.5 External Interrupts............................................................................ 38
6.6 Response Time.................................................................................... 39
Chapter 7. Timer/Counter 0/1.........................................................40
7.1 Timer/Counter 0 Mode of Operation................................................ 42
7.2 Timer/Counter 1 Mode of Operation................................................ 45
7.3 Baud Rate Generator and Programmable Clock Output on P1.0.. 47
Chapter 8. UART with enhanced function....................................48
8.1 UART Mode of Operation................................................................... 52
8.2 Frame Error Detection........................................................................ 58
8.3 Multiprocessor Communications...................................................... 58
8.4 Automatic Address Recognition.......................................................... 60
8.5 Buad Rates............................................................................................ 61
Chapter 9 In System Programming (ISP)/In Application Programming(IAP) 63
Chapter 10 STC10/11 xx series Selection Table..............................66
3
Chapter 1. Introduction
STC11F/10Fxx series are a single-chip microcontroller based on a high performance 1T architecture 80C51 CPU,
which is produced by STC MCU Limited. With the enhanced kernel, STC11F/10Fxx series execute instructions in
1~6 clock cycles (about 6~7 times the rate of a standard 8051 device), and have an fully compatible instruction
set with industrial-standard 80C51 series microcontroller . In-System-Programming (ISP) and In-Application-
Programming (IAP) support the users to upgrade the program and data in system. ISP allows the user to download
new code without removing the microcontroller from the actual end product; IAP means that the device can write
non-valatile data in Flash memory while the application program is running. The STC11F/10Fxx series retain all
features of the standard 80C51. In addition, the STC11F/10Fxx series have a extra I/O port (P4 ), a 6-sources,
2-priority-level interrupt structure, on-chip crystal oscillator,and a one-time enabled Watchdog Timer.
1.1 Features
• Enhanced 80C51 Central Processing Unit ,1T per machine cycle, faster 6~7 times than the rate of a standard
8051.
• Operating voltage range: 5.5~4.1V/3.7V or 2.1V/2.4V ~ 3.6V (STC11L/10Lxx series)
• Operating frequency range: 0- 35MHz, is equivalent to standard 8051:0~420MHZ
• On-chip 4/8/12/14/16/20/32/40/48/52/56/62K Flash program memory with flexible ISP/IAP capability,
• On-chip 1280/512/256 byte RAM
• Be capable of addressing up to 64K byte of external RAM
• Dual Data Pointer (DPTR) to speed up data movement
• Code protection for flash memory access
• two 16-bit timer/counter, as the same as Timer0/Timer1 of standard 8051,one BRT(Baud-rate-generator)
• 6 vector-address, 2 level priority interrupt capability
• One enhanced UART with hardware address-recognition, frame-error detection function, and with self baud-
rate generator.
• One 15 bits Watch-Dog-Timer with 8-bit pre-scaler (one-time-enabled)
• Simple internal RC oscillator
• Three power management modes: idle mode, slow down mode and power-down mode
• Power down mode can be woken-up by INT0/P3.0 pin, INT1/P3.3 pin, T0/P3.4, T1/P3.5, RXD/P3.0 pin (or
RXD/P1.6 pin)
• Maximum 40 programmable I/O ports are available
• Programable clock output Function. T0 output the clock on P3.4, T1 output the clock on P3.5, BRT output the
clock on P1.0.
• Five package type : LQFP-44, PDIP-40, PLCC-44, QFN-40
STC MCU Limited. 4

1.2 Block diagram
The CPU kernel of STC11/10Fxx series are fully compatible to the standard 8051 microcontroller, maintains
all instruction mnemonics and binary compatibility. With some great architecture enhancements, STC11/10Fxx
series execute the fastest instructions per clock cycle. Improvement of individual programs depends on the actual
instructions used.
AUX-RAM RAM ADDR

RAM
1024B Register
B Register ACC Stack FLASH

Poniter 64K
TMP2 TMP1 Timer 0/1 ISP/IAP
Enhanced
UART Address
Generator
ALU
WDT Program
PSW
Counter
LVD/LVR
Control Port 0,1,2,3,4

RESET Unit Latch
XTAL1 XTAL2
Port 0,1,2,3,4
Driver
P0, P1
P2,P3,P4
STC11/10Fxx Block Diagram
STC MCU Limited 5

1.3 Pin Configurations
ALE/P4.5
NA/P4.6
NA/P4.4
P0.4
P0.5
P0.6
P0.7
P4.1
P2.7
P2.6
P2.5
CLKOUT2/P1.0 1 40 Vcc
33
32
31
30
29
28
27
26
25
24
23
P1.1 2 39 P0.0
P0.3 34 22 P2.4 P1.2 3 38 P0.1
P0.2 35 21 P2.3
PDIP-40
P1.3 4 37 P0.2
P0.1 36 20 P2.2
37 P1.4 5 36 P0.3
P0.0 19 P2.1
38 P1.5 6 35 P0.4
Vcc
39
LQFP-44 18
17
P2.0
INT/RXD/P1.6 7 34 P0.5
P4.2 P4.0
P1.0/CLKOUT2 40 STC11/10Fxx 16 Gnd TXD/P1.7 8 33 P0.6
P1.1 41 15 XTAL1 P4.7/RST 9 32 P0.7
P1.2 42 14 XTAL2 INT/RxD/P3.0 10 31 NA/P4.6
STC111/10Fxx
P1.3 43 13 RD/P3.7 TxD/P3.1 11 30 ALE/P4.5
P1.4 44 12 INT0/P3.2 12 29 NA/P4.4
WR/P3.6
INT1/P3.3 13 28 P2.7
10
11
1
2
3
4
5
6
7
8
9
CLKOUT0/INT/T0/P3.4 14 27 P2.6
P4.7/RST
P1.5
INT/RXD/P1.6
TXD/P1.7
INT/RxD/P3.0
P4.3
TxD/P3.1
INT1/P3.3
CLKOUT0/INT/T0/P3.4
CLKOUT1/INT/T1/P3.5
INT0/P3.2
WR/P3.6 16 25 P2.4
RD/P3.7 17 24 P2.3
XTAL2 18 23 P2.2
XTAL1 19 22 P2.1
Gnd 20 21 P2.0
P1.0/CLKOUT2
P1.4
P1.3
P1.2
P1.1
P4.2
P0.0
P0.1
P0.2
P0.3
Vcc
6
5
4
3
2
1
44
43
42
41
40
P1.5 7 39 P0.4
STC11/10Fxx
INT/RXD/P1.6 8 38 P0.5
TXD/P1.7 9 37 P0.6
PLCC-44
P4.7/RST 10 36 P0.7
INT/RxD/P3.0 11 35 NA/P4.6
P4.3 12 34 P4.1
TxD/P3.1 13 33 ALE/P4.5
INT0/P3.2 14 32 NA/P4.4
INT1/P3.3 15 31 P2.7
18
19
20
21
22
23
24
25
26
27
28
WR/P3.6
RD/P3.7
XTAL2
XTAL1
Gnd
P4.0
P2.0
P2.1
P2.2
P2.3
P2.4
STC MCU Limited. 6

1.4 Pin Descriptions
MNEMONIC LQFP44 PDIP40 PLCC44 DESCRIPTION
P0.0 ~ P0.7 30-37 32-39 36~43 Port0 : Port0 is an 8-bit bi-directional I/O port with pull-
up resistance. Except being as GPIO, Port 0 is also the
multiplexed low-order address and data bus during accesses
to external program and data memory.
P1.0 ~ P1.7 40~44 1-8 2~9 Port1 : General-purposed I/O with weak pull-up resistance
1~3 inside. When 1s are written into Port1, the strong output
driving CMOS only turn-on two period and then the weak
pull-up resistance keep the port high.
P2.0 ~ P2.7 18-25 21-28 24~31 Port2 : Port2 is an 8-bit bi-directional I/O port with pull-
up resistance. Except being as GPIO, Port2 emits the high-
order address byte during accessing to external program and
data memory.
P3.0 ~ P3.7 5 10-17 11 Port3 : General-purposed I/O with weak pull-up resistance
7~13 13~19 inside. When 1s are written into Port1, the strong output
driving CMOS only turn-on two period and then the weak
pull-up resistance keep the port high. Port3 also serves the
functions of various special features .
P4.0~P4.3 Port4 : Port4 are extended I/O ports such like Port1.
P4.0 17 23
P4.1 28 34
P4.2 39 1
P4.3 6 12
RST/P4.7 4 9 10 RESET : A high on this pin for at least two machine cycles
will reset the device.
P4.6 29 31 35
P4.4 26 29 32
ALE/P4.5 27 30 33 Address Latch Enable : It is used for external data memory
cycles (MOVX)
XTAL1 15 19 21 Crystal 1: Input to the inverting oscillator amplifier.Receives
the external oscillator signal when an external oscillator is
used.
XTAL2 14 18 20 Crystal 2: Output from the inverting amplifier. This pin
should be floated when an external oscillator is used.
VCC 38 40 44 Power
Gnd 16 20 22 Ground
STC MCU Limited 7

1.5 Pin Package Drawings
LQFP-44 OUTLINE PACKAGE
D1
44 34
33
1 VARIATIONS (ALL DIMENSIONS SHOWN IN MM
SYMBOLS MIN. NOM MAX.
A - - 1.60
A1 0.05 - 0.15
E1
E
A2 1.35 1.40 1.45
c1 0.09 - 0.16
11 23 D 12.00
D1 10.00
E 12.00
12 22
b E1 10.00
e e 0.80
1 b(w/o plating) 0.25 0.30 0.35
A2
L 0.45 0.60 0.75

c1
L1 1.00REF
θ0 00 3.50 70
0.05MAX
NOTES:
1.JEDEC OUTLINE:MS-026 BSB
2.DIMENSIONS D1 AND E1 D0 NOT
INCLUDE MOLD PROTRUSION.
0.25
A1
ALLOWBLE PROTRUSION IS
GATE PLANE
0.25mm PER SIDE. D1 AND E1 ARE
SEATING PLANE
MAXIMUM PLASTIC BODY SIZE
θ0
DIMENSIONS IMCLUDING MOLD
L
MISMATCH.
L1 3.DIMENSION b DOES NOT INCLUDE
DAMBAR PROTRUSION.ALLOWBLE
DAMBAR PROTRUSION SHALL NOT
CAUSE THE LEAD WIDTH TO EXCEED
THE MAXIMUN b DIMNSION BY MORE
THAN 0.08mm.
STC MCU Limited. 8

PDIP-40 OUTLINE PACKAGE
θ
0
40 21
E1
eθ
E
1 20
C
H
A2
SEATING
A
PLANE
L
A1
0.050tyb.
0.001tyb.
SYMBOLS MIN NOR MAX
0.050tyb.
A - - 0.190
A1 0.015 - -
A2 0.015 0.155 0.160
C 0.008 - 0.015
D 2.025 2.060 2.070
E 0.600
E1 0.540 0.545 0.550
L 0.120 0.130 0.140
eθ 0.630 0.650 0.670
0 0 7 15
NOTE:
1.JEDEC OUTLINE :MS-011 AC
STC MCU Limited 9

PLCC-44 OUTLINE PACKAGE
He A
E A2
A1
17 7
b
18 6
b1
Hd
1
Gd
e
28 40
29 39
L
θ0
H
c
Ge
Y
Seating Plane DIMENSIONS IN

DIMENSIONS IN INCH
SYMBOLS MILLMETERS
MIN NOM MAX MIN NOM MAX
A 0.165 - 0.180 4.191 - 4.572
A1 0.020 - - 0.508 - -
A2 0.147 - 0.158 3.734 - 4.013
b1 0.026 0.028 0.032 0.660 0.711 0.813
b 0.013 0.017 0.021 0.330 0.432 0.533
c 0.007 0.010 0.0013 0.178 0.254 0.330
D 0.650 0.653 0.656 16.510 16.586 16.662
E 0.650 0.653 0.656 16.510 16.586 16.662
NOTE: e 0.050BSC 1.270BSC
Gd 0.590 0.610 0.630 14.986 15.494 16.002
1.JEDEC OUTLINE :M0-047 AC Ge 0.590 0.610 0.630 14.986 15.494 16.002
Hd 0.685 0.690 0.695 17.399 17.526 17.653
2.DATUM PLANE H IS LACATED AT THE He 0.685 0.690 0.695 17.399 17.526 17.653
BOTTOM OF THE MOLD PARTING LINE L 0.100 - 0.112 2.540 - 2.845
COINCIDENT WITH WHERE THE LEAD
Y - - 0.004 - - 0.102
EXITS THE BODY.
3.DIMENSIONS E AND D D0 NOT INCLUDE MODE

PROTRUSION. ALLOWABLE PROTRUSION IS 10
MIL PRE SIDE.DIMENSIONS E AND D D0 INCLUDE
MOLD MISMATCH AND ARE DETERMINED
AT DATUM PLANE H .
4.DIMENSION b1 DOES NOT INCLUDE DAMBAR

PROTRUSION.
STC MCU Limited. 10

Chapter 2. CLOCK, POWER MANAGENMENT, RESET
2.1 Clock Network
There are two clock sources available for STC11/10Fxx series. One is the clock from crystal oscillation and the
other is from internal simple RC oscillation.
CLK_DIV register (Clock Divider)

LSB
bit B7 B6 B5 B4 B3 B2 B1 B0
name - - - - - CLKS2 CLKS1 CLKS0
B2-B0 (CLKS2-CLKS0) :
000 clock source is not divided (default state)
001 clock source is divided by 2.
101 clock souece is divided by 32.
Not-divided 000
÷2 001
÷4 010
Internal system clock
÷8 011 (To CPU and peripherals)
SYSclk
÷16 100
÷32 101
÷64 110
÷128 111
CLKS2,CLKS1,CLKS0
Clock Structure
STC MCU Limited 11
2.2 Power Management
PCON register
LSB
name SMOD SMOD0 LVDF POF GF1 GF0 PD IDL
SMOD : Double baud rate bit when the UART is used in mode 1,2 or 3.
SMOD0 : SM0/FE bit select for SCON.7
LVDF : Low-Voltage Flag. It is set if the voltage is below the LVD reference voltage.
POF : Power-On flag. It is set by power-off-on action and can only cleared by software.
GF1 : General-purposed flag 1
GF0 : General-purposed flag 0
PD : Power-Down bit.
IDL : Idle mode bit.
2.2.1 Idle Mode
An instruction that sets IDL/PCON.0 causes that to be the last instruction executed before going into the idle
mode, the internal clock is gated off to the CPU but not to the interrupt, timer, WDT and serial port functions. The
CPU status is preserved in its entirety: the Stack Pointer, Program Counter, Program Status Word, Accumulator,
and all other registers maintain their data during Idle. The port pins hold the logical states they had at the time Idle
was activated. ALE and PSEN hold at logic high levels.
There are two ways to terminate the idle. Activation of any enabled interrupt will cause PCON.0 to be cleared by
hardware, terminating the idle mode. The interrupt will be serviced, and following RETI, the next instruction to
be executed will be the one following the instruction that put the device into idle.
The flag bits (GFO and GF1) can be used to give art indication if an interrupt occurred during normal operation
or during Idle. For example, an instruction that activates Idle can also set one or both flag bits. When Idle is
terminated by an interrupt, the interrupt service routine can examine the flag bits.
The other way to wake-up from idle is to pull RESET high to generate internal hardware reset.Since the clock
oscillator is still running, the hardware reset neeeds to be held active for only two system clock cycles(24 system
clock) to complete the reset.
2.2.2 Slow Down Mode
A divider is designed to slow down the clock source prior to route to all logic circuit. The operating frequency of
internal logic circuit can therefore be slowed down dynamically , and then save the power.
STC MCU Limited. 12

2.2.3 Power Down (PD) Mode
An instruction that sets PCON.1 cause that to be the last instruction executed before going into the PD mode.
In the PD mode, the on-chip oscillator is stopped. The contents of on-chip RAM and SFRs are maintained. The
power-down mode can be woken-up by RESET pin, external interrupt INT0 ~ INT1, RXD pin, T0 pin, T1 pin
and PCA input pins-cex0 and cex1. When it is woken-up by RESET, the program will execute from the address
0x0000. Be carefully to keep RESET pin active for at least 10ms in order for a stable clock. If it is woken-up from
I/O, the CPU will rework through jumping to related interrupt service routine. Before the CPU rework, the clock
is blocked and counted until 32768 in order for denouncing the unstable clock. To use I/O wake-up, interrupt-
related registers have to be enabled and programmed accurately before power-down is entered. Pay attention to
have at least one “NOP” instruction subsequent to the power-down instruction if I/O wake-up is used.
2.3 RESET Control

In STC12C5A60S2, there are 6 sources to generate internal reset. They are RESET (P4.7) pin, Watch-Dog-Timer,
software reset, On-chip power-on-reset and On-chip MAX810 POR timing delay.
2.3.1 Reset pin

The P4.7 pin, if configured as RESET pin function(default), is input pin for chip reset. A level change
of RESET pin have to keep at least 24 cycles plus 10us in order for CPU internal sampling use.
2.3.2 Power-On Reset (POR)

When VCC drops below the detection threshold of POR circuit, all of the logic circuits are reset.
When VCC goes back up again, an internal reset is released automatically after a delay of 32768 clocks. The
nominal POR detection threshold is around 1.9V for 3V device and 3.3V for 5V device.
2.3.3 Watch-Dog-Timer
An overflow of Watch-Dog-Timer will generate a internal reset.
WDT_CONTR: Watch-Dog-Timer Control Register

name WDT_FLAG - EN_WDT CLR_WDT IDLE_WDT PS2 PS1 PS0
WDT_FLAG : WDT reset flag.

0 : This bit should be cleared by software.
1 : When WDT overflows, this bit is set by hardware to indicate a WDT reset happened.
STC MCU Limited 13

2.3.4 Software RESET
Writing an “1” to SWRST bit in IAP_CONTR register will generate a internal reset.
IAP_CONTR: ISP/IAP Control Register

name IAPEN SWBS SWRST CMD_FAIL - WT2 WT1 WT0
IAPEN : ISP/IAP operation enable.
0 : Global disable all ISP/IAP program/erase/read function.
1 : Enable ISP/IAP program/erase/read function.
SWBS: software boot selection control.
0 : Boot from main-memory after reset.
1 : Boot from ISP memory after reset.
SWRST: software reset trigger control.
0 : No operation
1 : Generate software system reset. It will be cleared by hardware automatically.
CMD_FAIL: Command Fail indication for ISP/IAP operation.
0 : The last ISP/IAP command has finished successfully.
1 : The last ISP/IAP command fails. It could be caused since the access of flash memory was inhibited.
2.3.5 MAX810 power-on-reset delay
There is another on-chip POR delay circuit is integrated on STC11/10Fxx. This circuit is like MAX810 and is
controlled by configuring flash Option Register. Very long POR delay time – around 200ms will be generated by
this circuit once it is enabled.
STC MCU Limited. 14

Chapter 3. Memory Organization
3.1 Program Flash Memory
There is 60K-bytes of flash memory embedded for program and data storage. The design allows users to
configure it as like there are three individual partition banks inside. They are called AP region, IAP region and
ISP boot region. AP region is the space that user program is resided. IAP(In-Application-Program) region is the
nonvolatile data storage space that may be used to save important parameters by AP program. In other words, the
IAP capability of STC11/10Fxx series provide the user to read/write the user-defined on-chip data flash region
to save the needing in use of external EEPROM device. ISP boot region is the space that allows a specific
program we calls “ISP program” is resided. Inside the ISP region, the user can also enable read/write access to
a small memory space to store parameters for specific purposes. This small space is called “ISP data flash” and
can be enabled via programming NVM option registers. Generally, the purpose of ISP program is to fulfill AP
program upgrade without the need to remove the device from system. STC11/10Fxx series hardware catches the
configuration information since power-up duration and performs out-of-space hardware-protection depending
on pre-determined criteria. The criteria is AP region can be accessed by ISP program only, IAP region can be
accessed by ISP program and AP program, and ISP region is prohibited access from AP program and ISP program
itself. But if the “ISP data flash is enabled”, ISP program can read/write this space. When wrong settings on ISP-
IAP SFRs are done, The “out-of-space” happens and STC11/10Fxx series follow the criteria above, ignore the
trigger command.
F000H FF
60K Special Function

High 128 Bytes Registers (SFRS)
Program Flash Internal RAM
Memory
80
7F
Low 128 Bytes
Internal RAM
0000H
00
Program Flash Memory
On-chip Scratch-Pad RAM
FFFF
03FF
1024 Bytes
64K Bytes
expanded RAM External RAM
0000
Auxiliary RAM
0000
External RAM
STC MCU Limited 15

Figure 3b. The 8052 Data Memory
3.2 Data Memory
3.2.1 On-chip Scratch-Pad RAM
Just the same as the conventional 8051 micro-controller, there are 256 bytes of SRAM data memory plus 128
bytes of SFR space available on the STC11/10Fxx series. The lower 128 bytes of data memory may be accessed
through both direct and indirect addressing. The upper 128 bytes of data memory and the 128 bytes of SFR
space share the same address space. The upper 128 bytes of data memory may only be accessed using indirect
addressing. The 128 bytes of SFR can only be accessed through direct addressing. The lower 32 bytes of data
memory are grouped into 4 banks of 8 registers each. The RS0 and RS1 bits in PSW register select which register
bank is in use. Instructions using register addressing will only access the currently specified bank.
3.2.2 Auxiliary RAM

There are 1024 bytes of additional data RAM available on STC11/10Fxx series. They may be accessed by the
instructions MOVX @Ri or MOVX @DPTR. A control bit – XRAM located in AUXR.1 register is to control
access of auxiliary RAM. When set, disable the access of auxiliary RAM. When clear (ERAM=0), this auxiliary
RAM is the default target for the address range from 0x0000 to 0x03FF. If ERAM=0 and the target address is
over 0x03FF, switches to access external RAM automatically. When ERAM=0, the content in DPH is ignored
when the instruction MOVX @Ri is executed.
3.2.3 External RAM

There is 64K-byte addressing space available for STC11/10Fxx series to access external data RAM. Just the same
as the design in the conventional 8051, the port – P2, P0, ALE, P3.6 and P3.7 have alterative function for external
data RAM access. In addition, a new register BUS_SPEED (address: 0x8F) is design to stretch the cycle time of
MOVX instruction. In BUS_SPEED register, {ALES1 and ALES0} is to stretch the setup time and hold time with
respect to ALE negative edge and {RW2, RW1, RW0} is to stretch the pulse width of /WR(P3.6) and /RD(P3.7).
By using BUS_SPEED to change the instruction cycle time, STC11/10Fxx series can conformed to communicate
with both of fast and slow peripheral devices without loss of communication efficiency.
3.2.4 Special Function Register for RAM
For fast data movement, STC11/10Fxx series support two data pointers. They share the same SFR address and are
switched by the register bit – DPS.
STC MCU Limited. 16

AUXR register
LSB
name T0x12 T1x12 UART_M0x6 BRTR - BRTx12 XRAM S1BRS
T0x12
0 : The clock source of Timer 0 is SYSclk/12.
T1x12
UART_M0x6
0 : The baud-rate of UART in mode 0 is SYSclk/12.
1 : The baud-rate of UART in mode 0 is SYSclk/2.
BRTR
0 : The baud-rate generator of UART is stopped.
1 : The baud-rate generator of UART is enabled.
B3 : resevered.
BRTx12
0 : The baud-rate generator is incremented every 12 system clocks.
1 : The baud-rate generator is incremented every system clock.
XRAM
0 : On-chip auxiliary RAM is enabled and located at the address 0x0000 to 0x03FF.
For address over 0x03FF, off-chip external RAM becomes the target automatically.
1 : On-chip auxiliary RAM is always disabled.
S1BRS
0 : Timer 1 is used for the baud-rate generator.
1 : Timer 1 is released to use in other functions, and enhanced UART is used for the baud-rate generator.
STC MCU Limited 17

0xFFFF FFFFH
External
RAM 63KB
External
RAM 64KB
0x0400
0x03FF
Auxiliary RAM 1KB
0x0000
0000H
XRAM=0 XRAM=1
AUXR1 register
LSB
name UART_P1 - - - GF2 - - DPS
GF2 : General Flag. It can be used by software.
DPS : DPTR registers select bit.

0 : DPTR0 is selected(Default).
1 : The secondary DPTR(DPTR 1) is switched to use.
STC MCU Limited. 18

BUS_SPEED register
LSB
name - - ALES1 ALES0 - RWS2 RWS1 RWS0
{ALES1 and ALES0} :

00 : The P0 address setup time and hold time to ALE negative edge is one clock cycle
01 : The P0 address setup time and hold time to ALE negative edge is two clock cycles.
10 : The P0 address setup time and hold time to ALE negative edge is three clock cycles. (default)
11 : The P0 address setup time and hold time to ALE negative edge is four clock cycles.
{RWS2,RWS1,RWS0} :
000 : The MOVX read/write pulse is 1 clock cycle.
001 : The MOVX read/write pulse is 2 clock cycles.
011 : The MOVX read/write pulse is 4 clock cycles. (default)
When the target is on-chip auxiliary RAM, the setting on BUS_SPEED register is discarded by hardware.
Timing diagram for MOVX @DPTR, A without stretch

1 2 3 4 5 6 7 1 2 3 4 5 6 7
Clock
Weak pullup
P2 High-byte address FF High-byte address
Weak pullup
P0 Low-byte Address Data for writing FF Low-byte Address Data for writing
ALE
/WR
(P3.6)
MOVX write cycle MOVX write cycle
STC MCU Limited 19

Timing diagram for MOVX A, @DPTR without stretch
1 2 3 4 5 6 7 1 2 3 4 5 6 7
Clock
P2 High-byte address High-byte address
P0 Low-byte Address Data Port weak-pullup Low-byte Address Data Port weak-pullup
ALE
/RD
(P3.7)
MOVX read cycle MOVX read cycle
Timing diagram for MOVX @DPTR, A with stretch {RWS2,RWS1,RWS0} = 3’b111

Twr = 8 clock cycles (Twr is stretched by 7 cycles).
1 2 3 4 5 6 7 8 9 0 1 2 3 4
Clock
P2 High-byte address
P0 Low-byte Address Data for writing
ALE
/WR
(P3.6)
MOVX write cycle
Twr = (1+7) cycles
Timing diagram for MOVX @DPTR, A with stretch {RWS2,RWS1,RWS0} = 3’b111 and
{ALES1,ALES0} == 2’b11
The Trd is stretched by 7, so Twr = 8 clock cycles. TALES is stretched by 3, so TALES = 4 clock
cycles and TALEH = 4 clock cycles.
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
Clock
P2 High-byte address
weak-pullup weak-pullup
P0 Low-byte Address FF Data FF
ALE
/RD Trd = (1+7) cycles

(P3.7) ALE setup time ALE hold time
(1+3) cycles (1+3) cycles
MOVX read cycle
STC MCU Limited. 20

Chapter 4. Configurable I/O Ports
4.1 I/O Port Configurations
All port pins on STC11/10Fxx series may be independently configured to one of four modes : quasi-bidirectional
(standard 8051 port output), push-pull output, input-only or open-drain output .All port pins default to quasi-
bidirectional after reset. Each one has a Schmitt-triggered input for improved input noise rejection.
P4.5, and P4.7 are located at the pins-ALE, and RST of conventional 80C51. Pay attention that additional control
bits on P4SW register are used to enable the I/O port functions of these pins. Prior to use them as I/O port, the
users must set the corresponding bit to enable it.
4.1.1 Quasi-bidirectional I/O
Port pins in quasi-bidirectional output mode function similar to the standard 8051 port pins. A quasi-bidirectional
port can be used as an input and output without the need to reconfigure the port. This is possible because when
the port outputs a logic high, it is weakly driven, allowing an external device to pull the pin low. When the pin
outputs low, it is driven strongly and able to sink a large current. There are three pull-up transistors in the quasi-
bidirectional output that serve different purposes.
One of these pull-ups, called the “very weak” pull-up, is turned on whenever the port register for the pin contains
a logic “1”. This very weak pull-up sources a very small current that will pull the pin high if it is left floating.
A second pull-up, called the “weak” pull-up, is turned on when the port register for the pin contains a logic
“1” and the pin itself is also at a logic “1” level. This pull-up provides the primary source current for a quasi-
bidirectional pin that is outputting a 1. If this pin is pulled low by the external device, this weak pull-up turns off,
and only the very weak pull-up remains on. In order to pull the pin low under these conditions, the external device
has to sink enough current to over-power the weak pull-up and pull the port pin below its input threshold voltage.
The third pull-up is referred to as the “strong” pull-up. This pull-up is used to speed up low-to-high transitions on
a quasi-bidirectional port pin when the port register changes from a logic “0” to a logic “1”. When this occurs, the
strong pull-up turns on for two CPU clocks, quickly pulling the port pin high.
Vcc Vcc Vcc

2 clock
delay Weak
Strong Very weak
PORT
PORT PIN
LATCH DATA
INPUT
DATA
Quasi-bidirectional output
STC MCU Limited 21

4.1.2 Push-pull Output
The push-pull output configuration has the same pull-down structure as both the open-drain and the quasi-
bidirectional output modes, but provides a continuous strong pull-up when the port register conatins a logic “1”.
The push-pull mode may be used when more source current is needed from a port output. In addition, input path
of the port pin in this configuration is also the same as quasi-bidirectional mode.
Vcc
PORT
LATCH DATA PORT
PIN
INPUT
DATA
Push-pull output
4.1.3 Input-only Mode
The input-only configuration is a Schmitt-triggered input without any pull-up resistors on the pin.
INPUT PORT
DATA PIN
Input-only Mode
4.1.4 Open-drain Output
The open-drain output configuration turns off all pull-ups and only drives the pull-down transistor
of the port pin when the port register contains a logic “0”. To use this configuration in application, a
port pin must have an external pull-up, typically tied to VCC. The input path of the port pin in this
configuration is the same as quasi-bidirection mode.
PORT
PORT PIN
LATCH DATA
INPUT
DATA
Open-drain output
STC MCU Limited. 22

4.2 I/O Port Registers
All port pins on STC11/10Fxx series may be independently configured by software to one of four types on a bit-
by-bit basis,as shown in next Table.Two mode registers for each port select the output mode for each port pin.
Table: Configuration of I/O port mode.

PxM1.n PxM0.n Port Mode
0 0 Quasi-bidirectional
0 1 Push-Pull output
1 0 Input Only (High-impedance)
1 1 Open-Drain Output
P0M0 register
bit 7 6 5 4 3 2 1 0
name P0M0.7 P0M0.6 P0M0.5 P0M0.4 P0M0.3 P0M0.2 P0M0.1 P0M0.0
P0M1 register
bit 7 6 5 4 3 2 1 0
P1M0 register
bit 7 6 5 4 3 2 1 0
P1M1 register
bit 7 6 5 4 3 2 1 0
P2M0 register
bit 7 6 5 4 3 2 1 0
P2M1 register
bit 7 6 5 4 3 2 1 0
P3M0 register
bit 7 6 5 4 3 2 1 0
P3M1 register
bit 7 6 5 4 3 2 1 0
STC MCU Limited 23

P4M0 register
bit 7 6 5 4 3 2 1 0
P4M1 register
bit 7 6 5 4 3 2 1 0
P4SW register
bit D7 D6 D5 D4 D3 D2 D1 D0
name - NA_P4.6 ALE_P4.5 NA_P4.4 - - - -
NA_P4.6: Set this bit to enable P4.6. (Pin Location : Convention 80C51’s EA).
0 : the pin is always kept at weak-high state.
1 : the pin functions as P4.6.
ALE_P4.5 : Set this bit to switch ALE to become P4.5. (Pin Location : Convention 80C51’s ALE)
0 : the pin functions as ALE output for use in MOVX instruction only.
1 : the pin functions as P4.5.
NA_P4.4 : Set this bit to enable P4.4. (Pin Location : Convention 80C51’s PSEN)
0 : the pin is always kept at weak-high state.
1 : the pin functions as P4.4
STC MCU Limited. 24

Chapter 5 Instruction System
5.1 Special Function Registers
0/8 1/9 2/A 3/B 4/C 5/D 6/E 7/F

0F8H 0FFH
0F0H B 0F7H
0000,0000
0E8H 0EFH
0E0H ACC 0E7H

0000,0000
0D8H 0DFH
0D0H PSW 0D7H
0000,0000
0C8H 0CFH
0C0H P4 WDT_CONR IAP_DATA IAP_ADDRH IAP_ADDRL IAP_CMD IAP_TRIG IAP_CONTR 0C7H
1111,1111 xx00,0000 1111,1111 0000,0000 0000,0000 xxxx,xx00 xxxx,xxxx 0000,0000
0B8H IP SADEN P4SW 0BFH
x0x0,0000 0000,0000 x000,xxxx
0B0H P3 P3M1 P3M0 P4M1 P4M0 0B7H
1111,1111 0000,0000 0000,0000 0000,0000 0000,0000
0A8H IE SADDR WKTCL WKTCH 0AFH
00x0,0000
0000,0000 0000,0000 0xxx,0000
0A0H P2 BUS_SPEED AUXR1 Don't use 0A7H
1111,1111 xx10,x011 xxxx,0xx0
098H SCON SBUF BRT 09FH
0000,0000 xxxx,xxxx 0000,0000
090H P1 P1M1 P1M0 P0M1 P0M0 P2M1 P2M0 CLK_DIV 097H
1111,1111 0000,0000 0000,0000 0000,0000 0000,0000 0000,0000 0000,0000 xxxx,x000
088H TCON TMOD TL0 TL1 TH0 TH1 AUXR WAKE_CLKO 08FH
0000,0000 0000,0000 0000,0000 0000,0000 0000,0000 0000,0000 0000,x000 x000,x000
080H P0 SP DPL DPH PCON 087H
1111,1111 0000,0111 0000,0000 0000,0000 0011,0000
0/8 1/9 2/A 3/B 4/C 5/D 6/E 7/F
STC MCU Limited 25

Value after
Symbol Description Address Bit Address and Symbol Power-on or
MSB LSB Reset
P0 Port 0 80H P0.7 P0.6 P0.5 P0.4 P0.3 P0.2 P0.1 P0.0 1111 1111B
SP Stack Pointer 81H 0000 0111B
DPL Data Pointer Low 82H 0000 0000B
DPTR
DPH Data Pointer High 83H 0000 0000B
PCON Power Control 87H SMOD SMOD0 LVDF POF GF1 GF0 PD IDL 0011 0000B
TCON Timer Control 88H TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 0000 0000B
TMOD Timer Mode 89H GATE C/T M1 M0 GATE C/T M1 M0 0000 0000B
TL0 Timer Low 0 8AH 0000 0000B
TL1 Timer Low 1 8BH 0000 0000B
TH0 Timer High 0 8CH 0000 0000B
TH1 Timer High 1 8DH 0000 0000B
AUXR Auxiliary register 8EH T0x12 T1x12 UART_M0x6 BRTR - BRTx12 XRAM S1BRS 0000 0000B
CLK_Output - RXD_PIN_IE T1_PIN_IE T0_PIN_IE - BRTCLKO T1CLKO T0CLKO
Power down
WAKE_CLKO 8FH 0000 0000B
Wake-up control
register
P1 Port 1 90H P1.7 P1.6 P1.5 P1.4 P1.3 P1.2 P1.1 P1.0 1111 1111B
P1M1 P1 configuration 1 91H 0000 0000B
CLK_DIV Clock Divder 97h - - - - - CLKS2 CLKS1 CLKS0 xxxx x000B
SCON Serial Control 98H SM0/FE SM1 SM2 REN TB8 RB8 TI RI 0000 0000B
SBUF Serial Buffer 99H xxxx xxxxB
dedicated Baud-
BRT 9CH 0000 0000B
Rate Timer
P2 Port 2 A0H P2.7 P2.6 P2.5 P2.4 P2.3 P2.2 P2.1 P2.0 1111 1111B
BUS_SPEED Bus-Speed Control A1H - - ALES1 ALES0 - RWS2 RWS1 RWS0 xx10 x011B
AUXR1 Auxiliary register1 A2H UART_P1 - - - GF2 - - DPS 0xxx 0xx0B
IE Interrupt Enable A8H EA ELVD - ES ET1 EX1 ET0 EX0 0x00 0000B
SADDR Slave Address A9H 0000 0000B
P3 Port 3 B0H P3.7 P3.6 P3.5 P3.4 P3.3 P3.2 P3.1 P3.0 1111 1111B
P3M1 P3 configuration 1 B1H 0000 0000B
STC MCU Limited. 26

Value after
MSB LSB Reset
Interrupt Priority - PLVD PADC PS PT1 PX1 PT0 PX0
IP B8H 0000 0000B
Low
SADEN Slave Address Mask B9H 0000 0000B
P4SW Port 4 switch BBH - NA_P4.6 ALE_P4.5 NA_P4.4 - - - - x000 xxxxB
P4 Port 4 C0H P4.7 P4.6 P4.5 P4.4 P4.3 P4.2 P4.1 P4.0 1111 1111B
Watch-Dog-Timer WDT_FLAG - EN_WDT CLR_WDT IDLE_WDT PS2 PS1 PS0
WDT_CONTR C1H xx00 0000B
Control Register
ISP/IAP Flash Data
IAP_DATA C2H 1111 1111B
Register
ISP/IAP Flash
IAP_ADDRH C3H 0000 0000B
Address High
ISP/IAP Flash
IAP_ADDRL C4H 0000 0000B
Address Low
ISP/IAP Flash - - - - - - MS1 MS0
IAP_CMD C5H xxxx x000B
Command Register
ISP/IAP Flash
IAP_TRIG C6H xxxx xxxxB
Command Trigger
ISP/IAP Control IAPEN SWBS SWRST CMD_FAIL - WT2 WT1 WT0
IAP_CONTR C7H 0000 x000B
Register
Program Status CY AC F0 RS1 RS0 OV F1 P
PSW D0H 0000 0000B
Word
B B Register F0H 0000 0000B
Accumulator
ACC is the Accumulator register. The mnemonics for accumulator-specific instructions, however, refer to the
accumulator simply as A.
B-Register
The B register is used during multiply and divide operations. For other instructions it can be treated as another
scratch pad register.
Stack Pointer
The Stack Pointer register is 8 bits wide. It is incrementde before data is stored during PUSH and CALL
executions. While the stack may reside anywhee in on-chip RAM, the Stack Pointer is initialized to 07H after a
reset. This causes the stack to begin at location 08H.
STC MCU Limited 27

Program Status Word(PSW)
The program status word(PSW) contains several status bits that reflect the current state of the CPU. The PSW,
shown below, resides in the SFR space. It contains the Carry bit, the Auxiliary Carry(for BCD operation), the two
register bank select bits, the Overflow flag, a Parity bit and two user-definable status flags.
The Carry bit, other than serving the function of a Carry bit in arithmetic operations, also serves as the
“Accumulator” for a number of Boolean operations.
The bits RS0 and RS1 are used to select one of the four register banks shown in the previous page. A number of
instructions refer to these RAM locations as R0 through R7.
The Parity bit reflects the number of 1s in the Accumulator. P=1 if the Accumulator contains an odd number of 1s
and otherwise P=0.
PSW register
bit 7 6 5 4 3 2 1 0
name CY AC F0 RS1 RS0 OV F1 P
CY : Carry flag.
AC : Auxilliary Carry Flag.(For BCD operations)
F0 : Flag 0.(Available to the user for general purposes)
RS1: Register bank select control bit 1.
RS0: Register bank select control bit 0.
OV : Overflow flag.
F1 : Flag 1. User-defined flag.
P : Parity flag.
Data Pointer
The Data Pointer (DPTR) consists of a high byte (DPH) and a low byte (DPL). Its intended function is to hold a
16-bit address. It may be manipulated as a 16-bit register or as two independent 8-bit registers.
STC MCU Limited. 28

5.2 Addressing Modes
Direct Addressing(DIR)
In direct addressing the operand is specified by an 8-bit address field in the instruction. Only internal data RAM
and SFRs can be direct addressed.
Indirect Addressing(IND)
In indirect addressing the instruction specified a register which contains the address of the operand. Both internal
and external RAM can be indirectly addressed.
The address register for 8-bit addresses can be R0 or R1 of the selected bank, or the Stack Pointer.
The address register for 16-bit addresses can only be the 16-bit data pointer register – DPTR.
Register Instruction(REG)
The register banks, containing registers R0 through R7, can be accessed by certain instructions which carry a 3-bit
register specification within the opcode of the instruction. Instructions that access the registers this way are code
efficient because this mode eliminates the need of an extra address byte. When such instruction is executed, one
of the eight registers in the selected bank is accessed.
Register-Specific Instruction
Some instructions are specific to a certain register. For example, some instructions always operate on the
accumulator or data pointer,etc. No address byte is needed for such instructions. The opcode itself does it.
Immediate Constant(IMM)
The value of a constant can follow the opcode in the program memory.
Index Addressing
Only program memory can be accessed with indexed addressing and it can only be read. This addressing mode is
intended for reading look-up tables in program memory. A 16-bit base register(either DPTR or PC) points to the
base of the table, and the accumulator is set up with the table entry number. Another type of indexed
addressing is used in the conditional jump instruction.
In conditional jump, the destination address is computed as the sum of the base pointer and the
accumulator.
STC MCU Limited 29

5.3 Instruction Set Summary
Execution cycles of Execution cycles of

Mnemonic Description Byte conventional 8051 STC11F60XE
ARITHMETIC OPERATIONS
ADD A, Rn Add register to Accumulator 1 12 2
ADD A, direct Add ditect byte to Accumulator 2 12 3
ADD A, @Ri Add indirect RAM to Accumulator 1 12 3
ADD A, #data Add immediate data to Accumulator 2 12 2
ADDC A, Rn Add register to Accumulator with Carry 1 12 2
ADDC A, direct Add direct byte to Accumulator with Carry 2 12 3
ADDC A, @Ri Add indirect RAM to Accumulator with Carry 1 12 3
ADDC A, #data Add immediate data to Acc with Carry 2 12 2
SUBB A, Rn Subtract Register from Acc wih borrow 1 12 2
SUBB A, direct Subtract direct byte from Acc with borrow 2 12 3
SUBB A, @Ri Subtract indirect RAM from ACC with borrow 1 12 3
SUBB A, #data Substract immediate data from ACC with borrow 2 12 2
INC A Increment Accumulator 1 12 2
INC Rn Increment register 1 12 3
INC direct Increment direct byte 2 12 4
INC @Ri Increment direct RAM 1 12 4
DEC A Decrement Accumulator 1 12 2
DEC Rn Decrement Register 1 12 3
DEC direct Decrement direct byte 2 12 4
DEC @Ri Decrement indirect RAM 1 12 4
INC DPTR Increment Data Pointer 1 24 1
MUL AB Multiply A & B 1 48 4
DIV AB Divde A by B 1 48 5
DA A Decimal Adjust Accumulator 1 12 4
STC MCU Limited. 30

Execution cycles of Execution cycles of
Mnemonic Description Byte conventional 8051 STC11F60XE
LOGICAL OPERATIONS
ANL A, Rn AND Register to Accumulator 1 12 2
ANL A, direct AND direct btye to Accumulator 2 12 3
ANL A, @Ri AND indirect RAM to Accumulator 1 12 3
ANL A, #data AND immediate data to Accumulator 2 12 2
ANL direct, A AND Accumulator to direct byte 2 12 4
ANL direct,#data AND immediate data to direct byte 3 24 4
ORL A, Rn OR register to Accumulator 1 12 2
ORL A,direct OR direct byte to Accumulator 2 12 3
ORL A,@Ri OR indirect RAM to Accumulator 1 12 3
ORL A, #data OR immediate data to Accumulator 2 12 2
ORL direct, A OR Accumulator to direct byte 2 12 4
ORL direct,#data OR immediate data to direct byte 3 24 4
XRL A, Rn Exclusive-OR register to Accumulator 1 12 2
XRL A, direct Exclusive-OR direct byte to Accumulator 2 12 3
XRL A, @Ri Exclusive-OR indirect RAM to 1 12 3
Accumulator
XRL A, #data Exclusive-OR immediate data to 2 12 2
Accumulator
XRL direct, A Exclusive-OR Accumulator to direct byte 2 12 4
XRL direct,#data Exclusive-OR immediate data to direct 3 24 4
byte
CLR A Clear Accumulator 1 12 1
CPL A Complement Accumulator 1 12 2
RL A Rotate Accumulator Left 1 12 1
RLC A Rotate Accumulator Left through the 1 12 1
Carry
RR A Rotate Accumulator Right 1 12 1
RRC A Rotate Accumulator Right through the 1 12 1
Carry
SWAP A Swap nibbles within the Accumulator 1 12 1
STC MCU Limited 31

Execution cycles of Execution cycles
Mnemonic Description Byte conventional 8051 of STC11F60XE
DATA TRANSFER
MOV A, Rn Move register to Accumulator 1 12 1
MOV A, direct Move direct byte to Accumulator 2 12 2
MOV A,@Ri Move indirect RAM to 1 12 2
MOV A, #data Move immediate data to Accumulator 2 12 2
MOV Rn, A Move Accumulator to register 1 12 2
MOV Rn, direct Move direct byte to register 2 24 4
MOV Rn, #data Move immediate data to register 2 12 2
MOV direct, A Move Accumulator to direct byte 2 12 3
MOV direct, Rn Move register to direct byte 2 24 3
MOV direct,direct Move direct byte to direct 3 24 4
MOV direct, @Ri Move indirect RAM to direct byte 2 24 4
MOV direct,#data Move immediate data to direct byte 3 24 3
MOV @Ri, A Move Accumulator to indirect RAM 1 12 3
MOV @Ri, direct Move direct byte to indirect RAM 2 24 4
MOV @Ri, #data Move immediate data to indirect RAM 2 12 3
MOV DPTR,#data16 Move immdiate data to indirect RAM 2 12 3
MOVC A,@A+DPTR Move Code byte relative to DPTR to Acc 1 24 4
MOVC A, @A+PC Move Code byte relative to PC to Acc 1 24 4
MOVX A,@Ri Move External RAM(16-bit addr) to Acc 1 24 4
MOVX A,@DPTR Move External RAM(16-bit addr) to Acc 1 24 3
MOVX @Ri, A Move Acc to External RAM(8-bit addr) 1 24 3
MOVX @DPTR,A Move Acc to External RAM (16-bit addr) 1 24 3
PUSH direct Push direct byte onto stack 2 24 4
POP direct POP direct byte from stack 2 24 3
XCH A,Rn Exchange register with Accumulator 1 12 3
XCH A, direct Exchange direct byte with Accumulator 2 12 4
XCH A, @Ri Exchange indirect RAM with Accumulator 1 12 4
XCHD A, @Ri Exchange low-order Digit indirect RAM 1 12 4
with Acc
STC MCU Limited. 32

Execution cycles of Execution cycles
Mnemonic Description Byte conventional 8051 of STC11F60XE
BOOLEAN VARIABLE MANIPULATION
CLR C Clear Carry 1 12 1
CLR bit Clear direct bit 2 12 4
SETB C Set Carry 1 12 1
SETB bit Set direct bit 2 12 4
CPL C Complement Carry 1 12 1
CPL bit Complement direct bit 2 12 4
ANL C, bit AND direct bit to Carry 2 24 3
ANL C, /bit AND complement of direct bit to Carry 2 24 3
ORL C, bit OR direct bit to Carry 2 24 3
ORL C, /bit OR complement of direct bit to Carry 2 24 3
MOV C, bit Move direct bit to Carry 2 12 3
MOV bit, C Move Carry to direct bit 2 24 4
JC rel Jump if Carry is set 2 24 3
JNC rel Jump if Carry not set 2 24 3
JB bit, rel Jump if direct bit is set 3 24 4
JNB bit,rel Jump if direct bit is not set 3 24 4
JBC bit, rel Jump if direct bit is set & clear bit 3 24 5
PROGRAM BRANCHING
ACALL addr11 Absolute Subroutine Call 2 24 6
LCALL addr16 Long Subroutine Call 3 24 6
RET Return from Subroutine 1 24 4
RETI Return from interrupt 1 24 4
AJMP addr11 Absolute Jump 2 24 3
LJMP addr16 Long Jump 3 24 4
SJMP rel Short Jump (relative addr) 2 24 3
JMP @A+DPTR Jump indirect relative to the DPTR 1 24 3
JZ rel Jump if Accumulator is Zero 2 24 3
JNZ rel Jump if Accumulator is not Zero 2 24 3
CJNE A,direct,rel Compare direct byte to Acc and jump if 3 24 5
not equal
CJNE A,#data,rel Compare immediate to Acc and Jump if 3 24 4
not equal
CJNE Rn,#data,rel Compare immediate to register and Jump 3 24 4
if not equal
CJNE @Ri,#data,rel Compare immediate to indirect and jump 3 24 5
if not equal
DJNZ Rn, rel Decrement register and jump if not Zero 2 24 4
DJNZ direct, rel Decrement direct byte and Jump if not 3 24 5
Zero
NOP No Operation 1 12 1
STC MCU Limited 33

Chapter 6. Interrupt
There are 6 interrupt vector addresses available in STC11/10Fxx series. Associating with each interrupt vector,
the interrupt sources can be individually enabled or disabled by setting or clearing a bit in the registers IE. The
register also contains a global disable bit(EA), which can be cleared to disable all interrupts at once.
Each interrupt source has two corresponding bits to represent its priority. Higher-priority interrupt will be not
interrupted by lower-priority interrupt request. If two interrupt requests of different priority levels are received
simultaneously, the request of higher priority is serviced. If interrupt requests of the same priority level are
received simultaneously, an internal polling sequence determine which request is serviced. The following table
shows the internal polling sequence in the same priority level and the interrupt vector address.
Interrupt
Vector Polling Interrupt Priority Priority 0 Priority Interrupt
Interrupt Source Enable
address Sequence setting( IP) (lowest) 1 Request Control Bit
/INT0
0003H 0(highest) PX0 0 1 IE0 EX0/EA
(External interrupt 0)
Timer 0 000BH 1 PT0 0 1 TF0 ET0/EA
/INT1
0013H 2 PX1 0 1 IE1 EX1/EA
(External interrupt 1)
Timer1 001BH 3 PT1 0 1 TF1 ET1/EA
UART
0023H 4 PS 0 1 RI+TI ES/EA
(Serial Interface)
NA 002BH 5 1
LVD 0033H 6 PLVD 0 1 LVDF ELVD/EA
STC MCU Limited. 34

6.1 Interrupt Structure
Highest Priority
Level Interrupt
IE Register IP Register
EX0
/INT0 IE0
high
ET0
TF0
EX1
/INT1 IE1
ET1
TF1 Interrupt
ES
Polling
RI Sequence
TI
ELVD
LVDF
low
Lowest Priority
Global Enable Level Interrupt
EA
Interrupt system diagram of STC11/10Fxx series
STC MCU Limited 35

The External Interrupts INT0 and INT1 can each be either level-activated or transition-activated, depending
on bits IT0 and IT1 in Register TCON. The flags that actually generate these interrupts are bits IE0 and IE1
in TCON. When an external interrupt is generated, the flag that generated it is cleared by the hardware when
the service routine is vectored to if and only if the interrupt was transition –activated, otherwise the external
requesting source is what controls the request flag, rather than the on-chip hardware.
The Timer 0 and Timer1 Interrupts are generated by TF0 and TF1, which are set by a rollover in their respective
Timer/Counter registers in most cases. When a timer interrupt is generated, the flag that generated it is cleared by
the on-chip hardware when the service routine is vectored to.
The Serial Port Interrupt is generated by the logical OR of RI and TI. Neither of these flags is cleared by
hardware when the service routine is vectored to. In fact, the service routine will normally have to determine
whether it was RI and TI that generated the interrupt, and the bit will have to be cleared by software.
The Low Voltage Detect interrupt is generated by the flag – LVDF in PCON register. It should be cleared by
software.
All of the bits that generate interrupts can be set or cleared by software, with the same result as though it had
been set or cleared by hardware. In other words, interrupts can be generated or pending interrupts can be canceled
in software.
6.2 Interrupt Register

Value after
MSB LSB Reset
IP Interrupt Priority Low B8H - PLVD - PS PT1 PX1 PT0 PX0 0000 0000B
AUXR Auxiliary register 8EH T0x12 T1x12 UART_M0x6 BRTR - BRTx12 EXTRAM S1BRS 0000 0000B
CLK_Output Power PCAWAKEUP RXD_PIN_IE T1_PIN_IE T0_PIN_IE - BRTCLKO T1CLKO T0CLKO
WAKE_CLKO down Wake-up 8FH 0000 0000B

control register
STC MCU Limited. 36

IE: Interrupt Enable Rsgister
(MSB) (LSB)

EA ELVD - ES ET1 EX1 ET0 EX0
Enable Bit = 1 enables the interrupt .

Enable Bit = 0 disables it .
Symbol Position Function
disables all interrupts. if EA = 0,no interrupt will be acknowledged. if
EA IE.7 EA = 1, each interrupt source is individually enabled or disabled by
setting or clearing its enable bit.
ELVD IE.6 Low volatge detection interrupt enable bit.
ES IE.4 Serial Port interrupt enable bit
ET1 IE.3 Timer 1 interrupt enable bit
EX1 IE.2 External interrupt 1 enable bit
ET0 IE.1 Timer 0 interrupt enable bit
EX0 IE.0 External interrupt 0 enable bit
IP: Interrupt Priority Register
(MSB) (LSB)

- PLVD - PS PT1 PX1 PT0 PX0
Priority bit = 1 assigns high priority .

Priority bit = 0 assigns low priority.
Symbol Position Function
PLVD IP.6 Low voltage detection interrupt priority.

PS IP.4 Serial Port interrupt priority bit.
PT1 IP.3 Timer 1 interrupt priority bit
PX1 IP.2 External interrupt 1 priority bit
PT0 IP.1 Timer 0 interrupt priority bit
PX0 IP.0 External interrupt 0 priority bit
STC MCU Limited 37

6.3 Interrupt Priorities
Each interrupt source can also be individually programmed to one of two priority levels by setting or clearing a
bit in Special Function Register IP. A low-priority interrupt can itself be interrupted by a high-pority interrupt, but
not by another low-priority interrupt. A high-priority interrupt can’t be interrupted by any other interrupt source.
If two requests of different priority levels are received simultaneously, the request of higher priority level
is serviced. If requests of the same priority level are received simultaneously, an internal polling sequence
determines which request is serviced. Thus within each priority level there is a second priority structure
determined by the polling sequence,as follows:
Source Priority Within Level
0. IE0 (highest)
1. TF0
2. IE1
3. TF1
4. RI +Tl
5.
6. LVDF
Note that the “priority within level” structure is only used to resolve simultaneous requests of the same prionty
level.
6.4 How Interrupts Are Handled
External interrupt pins and other interrupt sources are sampled at the rising edge of each instruction OPcode
fetch cycle. The samples are polled during the next instruction OPcode fetch cycle. If one of the flags was in a set
condition of the first cycle, the second cycle of polling cycles will find it and the interrupt system will generate an
hardware LCALL to the appropriate service routine as long as it is not blocked by any of the following conditions.
Block conditions :
• An interrupt of equal or higher priority level is already in progress.

• The current cycle(polling cycle) is not the final cycle in the execution of the instruction in progress.
• The instruction in progress is RETI or any write to the IE or IP registers.
• The ISP/IAP activity is in progress.
Any of these four conditions will block the generation of the hardware LCALL to the interrupt service routine.
Condition 2 ensures that the instruction in progress will be completed before vectoring into any service routine.
Condition 3 ensures that if the instruction in progress is RETI or any access to IE or IP, then at least one or more
instruction will be executed before any interrupt is vectored to.
The polling cycle is repeated with the last clock cycle of each instruction cycle. Note that if an interrupt flag is
active but not being responded to for one of the above conditions, if the flag is not still active when the blocking
condition is removed, the denied interrupt will not be serviced. In other words, the fact that the interrupt flag
was once active but not being responded to for one of the above conditions, if the flag is not still active when the
blocking condition is removed, the denied interrupt will not be serviced. The interrupt flag was once active but
not serviced is not kept in memory. Every polling cycle is new.
STC MCU Limited. 38

Note that if an interrupt of higher priority level goes active prior to S5P2 of the machine cycle labeled C3, then
in accordance with the above rules it will be vectored to during C5 and C6, without any instruction of the lower
priority routine having been executed.
Thus the processor acknowledges an interrupt request by executing a hardware-generated LCALL to the
appropriate servicing routine. In some cases it also clears the flag that generated the interrupt, and in other cases
it doesn’t. It never clears the Serial Port flags. This has to be done in the user’s software. It clears an external
interrupt flag (IE0 or IE1) only if it was transition-activated. The hardware-generated LCALL pushes the contents
of the Program Counter onto the stack (but it does not save the PSW) and reloads the PC with an address that
depends on the source of the interrupt being vectored to, as shown be low.
Source Vector Address
IE0 0003H
TF0 000BH
IE1 0013H
TF1 001BH
RI+TI 0023H
None 002BH
LVDF 0033H
Execution proceeds from that location until the RETI instruction is encountered. The RETI instruction informs
the processor that this interrupt routine is no longer in progress, then pops the top two bytes from the stack and
reloads the Program Counter. Execution of the interrupted program continues from where it left off.
Note that a simple RET instruction would also have returned execution to the interrupted program, but it would
have left the interrupt control system thinking an interrupt was still in progress.
6.5 External Interrupts
The external sources can be programmed to be level-activated or transition-activated by setting or clearing bit IT1
or IT0 in Register TCON. If ITx = 0, external interrupt x is triggered by a detected low at the INTx pin. If ITx=1,
external interrupt x is edge-triggered. In this mode if successive samples of the INTx pin show a high in one cycle
and a low in the next cycle, interrupt request flag IEx in TCON is set. Flag bit IEx then requests the interrupt.
Since the external interrupt pins are sampled once each machine cycle, an input high or low should hold for at
least 12 oscillator periods to ensure sampling. If the external interrupt is transition-activated, the external source
has to hold the request pin high for at least one machine cycle, and then hold it low for at least one machine cycle
to ensure that the transition is seen so that interrupt request flag IEx will be set. IEx will be automatically cleared
by the CPU when the service routine is called.
If the external interrupt is level-activated, the external source has to hold the request active until the requested
interrupt is actually generated. Then it has to deactivate the request before the interrupt service routine is
completed, or else another interrupt will be generated.
STC MCU Limited 39

6.6 Response Time
The INT0 and INT1 levels are inverted and latched into the interrupt flags IE0 and IE1 at rising edge of every
syetem clock cycle.
The Timer 0 and Timer 1 flags, TF0 and TF1, are set after which the timers overflow. The values are then polled
by the circuitry at rising edge of the next system clock cycle.
If a request is active and conditions are right for it to be acknowledged, a hardware subroutine call to the
requested service routine will be the next instruction to be executed. The call itself takes six system clock cycles.
Thus, a minimum of seven complete system clock cycles elapse between activation of an external interrupt
request and the beginning of execution of the first instruction of the service routine.
A longer response time would result if the request is blocked by one of the four previously listed conditions. If an
interrupt of equal or higher priority level is already in progress, the additional wait time obviously depends on the
nature of the other interrupt’s service routine. If the instruction in progress is not in its final cycle, the additional
wait time cannot be more than 3 cycles, since the longest instructions (LCALL) are only 6 cycles long, and if the
instruction in progress is RETI or an access to IE or IP, the additional wait time cannot be more than 5 cycles (a
maximum of one more cycle to complete the instruction in progress, plus 6 cycles to complete the next instruction
if the instruction is LCALL).
Thus, in a single-interrupt system, the response time is always more than 7 cycles and less than 12 cycles.
STC MCU Limited. 40

Chapter 7. Timer/Counter 0/1
Timer 0 and timer 1 are like the ones in the conventional 8051, both of them can be individually configured as
timers or event counters.
In the “Timer” function, the register is incremented every 12 cycles or every cycle depending on AUXR.7(T0x12)
bit and AUXR.6(T1x12). In the default state, it is fully the same as the conventional 8051. In the x12 mode, the
count rate equals to the oscillator frequency.
In the “Counter” function, the register is incremented in response to a 1-to-0 transition at its corresponding
external input pin, T0 or T1. In this function, the external input is sampled once at the positive edge of every
clock cycle. When the samples show a high in one cycle and a low in the next cycle, the count is incremented.
The new count value appears in the register during S3P1 of the cycle following the one in which the transition
was detected. Since it takes 2 machine cycles(24 oscillator periods) to recognize a l-to-0 transition, the maximum
count rate is 1/24 of the oscillator frequency. There are no restrictions on the duty cycle of the external input sig-
nal, but to ensure that a given level is sampled at least once before it changes, it should be held for at least one full
machine cycle.
In addition to the “Timer” or “Counter” selection, Timer 0 and Timer 1 have four operating modes from which
to select. The “Timer” or “Counter” function is selected by control bits C/T in the Speciai Function Register
TMOD. These two Timer/Counter have four operating modes, which are selected by bit-pairs (M1, M0) in
TMOD. Modes 0, 1, and 2 are the same for both Timer/Counters. Mode 3 is different.The four operating modes
are described in the following text.
Value after
MSB LSB Reset
TL0 Timer Low 0 8AH 0000 0000B
TH0 Timer High 0 8CH 0000 0000B
Power down
Wake-up control
register
STC MCU Limited 41

AUXR register
LSB
B7 B6 B5 B4 B3 B2 B1 B0
T0x12 T1x12 UART_M0x6 BRTR - BRTx12 XRAM S1BRS
T0x12
T1x12
WAKE_CLKO:CLK_Output Power down Wake-up control register
B7 B6 B5 B4 B3 B2 B1 B0
- RXD_PIN_IE T1_PIN_IE T0_PIN_IE - BRTCLKO T1CLKO T0CLKO
BRTCLKO : When set, P1.0 is enabled to be the clock output of Baud-Rate Timer (BRT). The clock rate is
BRT overflow rate divided by 2.
T1CLKO : When set, P3.5 is enabled to be the clock output of Timer 1. The clock rate is Timer1
overflow rate divided by 2.
T0CLKO : When set, P3.4 is enabled to be the clock output of Timer 0. The clock rate is Timer0
TMOD register : Timer/Counter Mode Control Register
(MSB) (LSB)
GATE C/T M1 M0 GATE C/T M1 M0
}
}
Timer 1 Timer 0
Gating control when set. Timer/Counter "x" is enabled only while " INTx " pin is high and
GATE
"TRx"control pin is set.When cleared Timer "x" is enabled whenever "TRx" control bit is set.
Timer or Counter Selector cleared for Timer operation (input from internal system clock). Set for
C/T
Counter operation (input from "Tx" input pin).
M0 M1 Operating Mode
0 0 B-bit Timer/Counter "THx" with "TLx" as 5-bit prescaler.
0 1 16-bit Timer/Counter"THx"and"TLx"are cascaded;there is no prescaler
8-bit auto-reload Timer/Counter “THx” holds a value which is to be reloaded into “TLx”
1 0
each time it overflows.
(Timer 0) TL0 is an 8-bit Timer/Counter controlled by the standard Timer 0 control bits
1 1
TH0 is an 8-bit timer only controlled by Timer 1 control bits.
1 1 (Timer 1) Timer/Counter 1 stopped
STC MCU Limited. 42

TCON register: Timer/Counter Control Register
(MSB) (LSB)
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Symbol Position Name and Significance Symbol Position Name and Significance
TF1 TCON.7 Timer 1 overflow Flag. Set by IE1 TCON.3 Interrupt 1 Edge flag. Set by
hardware on Timer/Counter overflow. hardware when external interrupt
cleared by hardware when processor edge detected.Cleared when
vectors to interrupt routine. interrupt processed.
TR1 TCON.6 Timer 1 Run control bit. Set/cleared IT1 TCON.2 Intenupt 1 Type control bit. Set/
cleared by software to specify
by software to turn Timer/Counter
falling edge/low level triggered
on/off.
external interrupts.
TF0 TCON.5 Timer 0 overflow Flag. Set by IE0 TCON.1 Interrupt 0 Edge flag. Set by
hardware on Timer/Counter overflow. hardware when external interrupt
cleared by hardware when processor edge detected.Cleared when
vectors to interrupt routine. interrupt processed.
TR0 TCON.4 Timer 0 Run control bit. Set/cleared IT0 TCON.0 Intenupt 0 Type control bit. Set/
cleared by software to specify
by software to turn Timer/Counter
falling edge/low level triggered
on/off.
external interrupts.
7.1 Timer/Counter 0 Mode of Operation
Mode 0
In this mode, the timer register is configured as a 13-bit register. As the count rolls over from all 1s to all 0s, it
sets the timer interrupt flag TF0. The counted input is enabled to the timer when TR0 = 1 and either GATE=0 or
INT0 = 1.(Setting GATE = 1 allows the Timer to be controlled by external input INT0 , to facilitate pulse width
measurements.) TR0 is a control bit in the Special Function Register TCON. GATE is in TMOD.
The 13-Bit register consists of all 8 bits of TH0 and the lower 5 bits of TL0. The upper 3 bits of TL0 are
indeterminate and should be ignored. Setting the run flag (TR0) does not clear the registers.
There are two different GATE bits. one for Timer 1 (TMOD.7) and one for Timer 0 (TMOD.3).
AUXR.7/T0x12=0
÷12
SYSclk
÷1
AUXR.7/T0x12=1
C/T=0 TL0 TH0
TF0 Interrupt
C/T=1 (5 Bits) (8 bits)
T0 Pin
control
TR0
GATE
INT0
Timer/Counter 0 Mode 0: 13-Bit Counter

STC MCU Limited 43
Mode 1
The 16-Bit register consists of all 8 bits of TH0 and the lower 8 bits of TL0. Setting the run flag (TR0) does not
clear the registers.
Mode 1 is the same as Mode 0, except that the timer register is being run with all 16 bits.
AUXR.7/T0x12=0
÷12
SYSclk
÷1
AUXR.7/T0x12=1
C/T=0 TL0 TH0
TF0 Interrupt
T0 Pin
TR0 control
GATE
INT0
Timer/Counter 0 Mode 1 : 16-Bit Counter
Mode 2
Mode 2 configures the timer register as an 8-bit counter(TL0) with automatic reload. Overflow from TL0 not
only set TF0, but also reload TL0 with the content of TH0, which is preset by software. The reload leaves TH0
unchanged.
STC12C5A60S2 is able to generate a programmable clock output on P3.4. When T0CLKO bit in
WAKE_CLKO SFR is set, T0 timer overflow pulse will toggle P3.4 latch to generate a 50% duty clock.
The frequency of clock-out is as following :
(SYSclk/2) / (256 – TH0), when T0x12=1

or (SYSclk/2/12) / (256 – TH0) , when T0x1=0
STC MCU Limited. 44

AUXR.7/T0x12=0
÷12 TF0 Interrupt
SYSclk
÷1 Toggle
AUXR.7/T0x12=1
C/T=0 TL0
(8 Bits)
CLKOUT0
T0 Pin C/T=1
control P3.4
TR0
GATE T0CLKO
TH0
INT0 (8 Bits)
Timer/Counter 0 Mode 2: 8-Bit Auto-Reload
Mode 3
Timer 1 in Mode 3 simply holds its count, the effect is the same as setting TR1 = 0. Timer 0 in Mode 3 established
TL0 and TH0 as two separate 8-bit counters. TL0 use the Timer 0 control bits: C/T ,GATE,TR0, INT0 and TF0.
TH0 is locked into a timer function (counting machine cycles) and takes over the use of TR1 from Tmer 1. Thus,
TH0 now controls the “Timer 1” interrupt.
Mode 3 is provided for applications requiring an extra 8-bit timer or counter. When Timer 0 is in Mode 3, Timer 1
can be turned on and off by switching it out of and into its own Mode 3, or can still be used by the serial port as a
baud rate generator, or in fact, in any application not requiring an interrupt.
AUXR.7/T0x12=0
÷12
SYSclk
÷1
AUXR.7/T0x12=1
C/T=0 TL0
TF0 Interrupt
C/T=1 (8 bit)
T0 Pin
control
TR0
GATE
INT0
AUXR.7/T0x12=0
÷12
SYSclk TH0 TF1

(8 Bits) Interrupt
÷1
AUXR.7/T0x12=0
control
TR1
Timer/Counter 0 Mode 3: Two 8-Bit Counters
STC MCU Limited 45

7.2 Timer/Counter 1 Mode of Operation
Mode 0
The 13-Bit register consists of all 8 bits of TH1 and the lower 5 bits of TL1. The upper 3 bits of TL1 are
indeterminate and should be ignored. Setting the run flag (TR1) does not clear the registers.
AUXR.6/T1x12=0
÷12
SYSclk
÷1
AUXR.6/T1x12=1
C/T=0 TL1 TH1
TF1 Interrupt
T1 Pin
control
TR1
GATE
INT1
Timer/Counter 1 Mode 0: 13-Bit Counter
Mode 1
measurements.) TRl is a control bit in the Special Function Register TCON. GATE is in TMOD.
The 16-Bit register consists of all 8 bits of THl and the lower 8 bits of TL1. Setting the run flag (TR1) does not
clear the registers.
Mode 1 is the same as Mode 0, except that the timer register is being run with all 16 bits.
AUXR.6/T1x12=0
÷12
SYSclk
÷1
AUXR.6/T1x12=1
C/T=0 TL1 TH1
TF1 Interrupt
T1 Pin
control
TR1
GATE
INT1
Timer/Counter 1 Mode 1 : 16-Bit Counter
STC MCU Limited. 46

Mode 2
Mode 2 configures the timer register as an 8-bit counter(TL1) with automatic reload. Overflow from TL1 not
only set TFx, but also reload TL1 with the content of TH1, which is preset by software. The reload leaves TH1
unchanged.
STC11/10Fxx series is able to generate a programmable clock output on P3.5. When T0CLKO bit in
WAKE_CLKO SFR is set, T1 timer overflow pulse will toggle P3.5 latch to generate a 50% duty clock.
The frequency of clock-out is as following :
(SYSclk/2) / (256 – TH1), when T1x12=1

or (SYSclk/2/12) / (256 – TH1) , when T1x1=0
AUXR.6/T1x12=0
÷12 TF1 Interrupt
SYSclk
÷1 Toggle
AUXR.6/T1x12=1
C/T=0 TL1
C/T=1 (8 Bits)
T1 Pin
control P3.5
TR1
GATE T1CLKO
TH1
INT1 (8 Bits)
Timer/Counter 1 Mode 2: 8-Bit Auto-Reload
STC MCU Limited 47

7.3 Baud Rate Generator and Programmable Clock Output on P1.0
AUXR.2/BRTx12=0
÷12
Toggle
SYSclk 8 Bits
Timer CLKOUT2
÷1
AUXR.2/BRTx12=1
P1.0
BRT2 BRTCLKO
BRT
STC11/10Fxx series are able to generate a programmable clock output on P1.0. When BRTCLKO bit in
WAKE_CLKO is set, BRT timer overflow pulse will toggle P1.0 latch to generate a 50% duty clock. The
frequency of clock-out is as following :
(SYSclk/2) / (256 –BRT), when BRTx12=1

or (SYSclk/2/12) / (256 – BRT) , when BRTx1=0
STC MCU Limited. 48

Chapter 8. UART with enhanced function
The serial port is full duplex,meaning it can transmit and receive simultaneously. It is also receive-buffered,
meaning it can commence reception of a second byte before a previously received byte has been read from the
reeeive register. (However,if the first byte still hasn’t been read by the time reception of the second byte
is complete, one of the bytes will be lost). The serial port receive and transmit share the same SFR – SBUF,
but actually there is two SBUF in the chip, one is for transmit and the other is for receive. The serial port can be
operated in 4 different modes.
Value after
MSB LSB Reset
BRT Baud-Rate Timer 9CH 0000 0000B
SBUF Serial Buffer 99H xxxx xxxxB
Interrupt Priority - PLVD - PS PT1 PX1 PT0 PX0
IP B8H 0000 0000B
Low
Slave Address
SADEN B9H 0000 0000B
Mask
SADDR Slave Address A9H 0000 0000B
AUXR1 Auxiliary register1 A2H UART_P1 - - - GF2 - - DPS 0xxx 0xx0B
Power down
Wake-up control
register
STC MCU Limited 49

SCON register
LSB
bit 7 6 5 4 3 2 1 0
name SM0/FE SM1 SM2 REN TB8 RB8 TI RI
FE: Framing Error bit. The SMOD0 bit must be set to enable access to the FE bit
0: The FE bit is not cleared by valid frames but should be cleared by software.
1: This bit set by the receiver when an invalid stop bit id detected.
SM0,SM1 : Serial Port Mode Bit 0/1.
SM0 SM1 Description Baud rate
0 0 8-bit shift register SYSclk/12
0 1 8-bit UART variable
1 0 9-bit UART SYSclk/64 or SYSclk/32(SMOD=1)
1 1 9-bit UART variable
SM2 : Enable the automatic address recognition feature in mode 2 and 3. If SM2=1, RI will not be
set unless the received 9th data bit is 1, indicating an address, and the received byte is a
Given or Broadcast address. In mode1, if SM2=1 then RI will not be set unless a valid stop
Bit was received, and the received byte is a Given or Broadcast address. In mode 0, SM2 should be 0.
REN : When set enables serial reception.
TB8 : The 9th data bit which will be transmitted in mode 2 and 3.
RB8 : In mode 2 and 3, the received 9th data bit will go into this bit.
TI : Transmit interrupt flag.
RI : Receive interrupt flag.
SBUF register
LSB
bit 7 6 5 4 3 2 1 0
name
It is used as the buffer register in transmission and reception.
BRT register
LSB
bit 7 6 5 4 3 2 1 0
name
It is used as the reload register for generating the baud-rate of the secondary UART.
PCON: Power Control register

LSB
bit 7 6 5 4 3 2 1 0
name SMOD SMOD0 LVDF POF GF1 GF0 PD IDL
SMOD: double Baud rate control bit.
0 : Disable double Baud rate of the UART.
1 : Enable double Baud rate of the UART in mode 1,2,or 3.
SMOD0: Frame Error select.
0 : SCON.7 is SM0 function.
1 : SCON.7 is FE function. Note that FE will be set after a frame error regardless of the state of SMOD0.
STC MCU Limited. 50

AUXR register
LSB
name T0x12 T1x12 UART_M0x6 BRTR - BRTx12 XRAM S1BRS
T1x12
UART_M0x6 : Serial Port mode 0 baud rate selector.
0 : Clear to select SYSclk/12 as the baud rate for UART Mode 0.
1 : Set to select SYSclk/2 as the baud rate for UART Mode 0.
BRTR: Independent Baud-rate generator control bit.
0 : The independent baud-rate generator is stoped
1 : The independent baud-rate generator is stoped
BRTx12
0 : The independent baud-rate is incremented every 12 system clocks.
1 : The independent baud-rate is incremented every system clock.
S1BRS
0 : select Timer 1 as the baud-rate generator of the enhanced UART .
1 : Timer 1 is replaced by the independent baud-rate generator for use of the enhanced UART. In other word,
time1 is released to use in other functions.
SADEN: Slave Address Mask register

LSB
name
SADDR: Slave Address register

LSB
name
SADDR register is combined with SADEN register to form Given/Broadcast Address for automatic address
recognition. In fact, SADEN function as the "mask" register for SADDR register. The following is the example
for it.
SADDR = 1100 0000
SADEN = 1111 1101
Given = 1100 00x0 The Given slave address will be checked except bit 1 is
treated as "don't care".
The Broadcast Address for each slave is created by taking the logical OR of SADDR and SADEN. Zero in this
result is considered as "don't care" and a Broad cast Address of all " don't care". This disables the automatic
address detection feature.
STC MCU Limited 51

AUXR1 register
LSB
name UART_P1 - - - GF2 - - DPS
UART_P1
0 : UART on Port 3(RXD/P3.0, TXD/P3.1).
1 : UART on Port 1(RXD/P1.6,TXD/P1.7).
GF2 : General Flag. It can be used by software.
DPS
0 : DPTR0 is selected(Default).
1 : The secondary DPTR(DPTR1) is switched to use.
WAKE_CLKO register
name - RXD_PIN_IE T1_PIN_IE T0_PIN_IE - BRTCKLO T1CKLO T0CKLO
RXD_PIN_IE :When set and the associated-UART interrupt control registers is configured correctly, the RXD pin
(P3.0) is enabled to wake up MCU from power-down state.
T1_PIN_IE :When set and the associated-Timer1 interrupt control registers is configured correctly, the T1 pin
T0_PIN_IE :When set and the associated-Timer0 interrupt control registers is configured correctly, the T1 pin
BRTCKLO : When set, P1.0 is enabled to be the clock output of Baud-Rate Timer (BRT). The clock rate is BRG
T1CKLO : When set, P3.5 is enabled to be the clock output of Timer 1. The clock rate is Timer 1overflow rate
divided by 2.
T0CKLO : When set, P3.4 is enabled to be the clock output of Timer 0. The clock rate is Timer 0overflow rate
divided by 2.
STC MCU Limited. 52

8.1 UART Mode of Operation
Mode 0
Serial data enters and exits through RXD. TXD outputs the shift clock. Eight data bits are transmitted/
received with the LSB first. The baud rate is fixed at 1/12 the System clock cycle in the default state. If
AUXR.5(UART_M0x6) is set, the baud rate is 1/2 System clock cycle.
Transmission is initiated by any instruction that uses SBUF as a destination register. The “write to SBUF” signal
also loads a “1” into the 9th position of the transmit shift register and tells the TX Control block to commence a
transmission. The internal timing is such that one full system clock cycle will elapse between "write to SBUF,"
and activation of SEND.
SEND transfers the output of the shift register to the alternate output function line of P3.0, and also transfers Shift
Clock to the alternate output function line of P3.1. At the falling edge of the Shift Clock, the contents of the shift
register are shifted one position to the right.
As data bits shift out to the right, “0” come in from the left. When the MSB of the data byte is at the output
position of the shift register, then the “1” that was initially loaded into the 9th position is just to the left of the
MSB, and all positions to the left of that contains zeroes. This condition flags the TX Control block to do one last
shift and then deactivate SEND and set TI. Both of these actions occur after "write to SBUF".
Reception is initiated by the condition REN=1 and RI=0. After that, the RX Control unit writes the bits 11111110
to the receive shift register, and in the next clock phase activates RECEIVE. RECEIVE enables SHIFT CLOCK
to the alternate output function line of P3.1.At RECEIVE is active, the contents of the receive shift register are
shifted to the left one position. The value that comes in from the right is the value that was sampled at the P3.0
pin the rising edge of Shift clock.
As data bits come in from the right, “1”s shift out to the left. When the “0” that was initially loaded into the right-
most position arrives at the left-most position in the shift register, it flags the RX Control block to do one last shift
and load SBUF. Then RECEIVE is cleared and RI is set.
STC MCU Limited 53

8051 INTERNAL BUS
WRITE
TO
SBUF DS Q SBUF
RXD/P3.0
OUTPUT FUNCTION
CL
SHIFT
ZERO DETECTOR
START SHIFT
SYSclk/12 0 TX CONTROL
TX CLOCK TI SEND
1 SERIAL
SYSclk/2 PORT
INTERRUPT SHIFT TXD/P3.1
RX CLOCK RI CLOCK OUTPUT FUNCTION
RECEIVE
RX CONTROL SHIFT
REN START 1 1 1 1 1 1 1 0
RI
INPUT SHIFT REG. RXD/P3.0

INPUT FUNCTION
LOAD
SBUF SHIFT
SBUF
READ
SBUF
8051 INTERNAL BUS
WRITE TO SBUF
S6P2
SEND
SHIFT
TRANSMIT
RXD(DATA OUT) D0 D1 D2 D3 D4 D5 D6 D7
TXD(SHIFT CLOCK)
TI
WRITE TO SCON(CLEAR RI)
RI
RECEIVE
SHIFT RECEIVE
D0 D1 D2 D3 D4 D5 D6 D7
RXD(DATA IN)
TXD(SHIFT CLOCK)
Serial Port Mode 0

STC MCU Limited. 54
Mode 1
10 bits are transmitted through TXD or received through RXD. The frame data includes a start bit(0), 8 data bits
and a stop bit(1). One receive, the stop bit goes into RB8 in SFR – SCON. The baud rate is determined by the
Timer 1 or BRT overflow rate.
Baud rate in mode 1 = (2SMOD /32 ) x timer 1 overflow rate ( if AUXR.0/S1BRS=0 )

= (2SMOD /32 ) x BRT overflow rate ( if AUXR.0/S1BRS=1 )
Transmission is initiated by any instruction that uses SBUF as a destination register. The “write to SBUF”
signal also loads a “1” into the 9th bit position of the transmit shift register and flags the TX Control unit that a
transmission is requested. Transmission actually happens at the next rollover of divided-by-16 counter. Thus the
bit times are synchronized to the divided-by-16 counter, not to the “write to SBUF” signal.
The transmission begins with activation of SEND , which puts the start bit at TXD. One bit time later, DATA is
activated, which enables the output bit of the transmit shift register to TXD. The first shift pulse occurs one bit
time after that.
As data bits shift out to the right, zeroes are clocked in from the left. When the MSB of the data byte is at the
output position of the shift register, then the 1 that was initially loaded into the 9th position is just to the left of the
MSB, and all positions to the left of that contain zeroes. This condition flags the TX Control unit to do one last
th
shift and then deactivate SEND and set TI. This occurs at the 10 divide-by-16 rollover after “write to SBUF.”
Reception is initiated by a 1-to-0 transition detected at RXD. For this purpose, RXD is sampled at a rate of 16
times the established baud rate. When a transition is detected, the divided-by-16 counter is immediately reset,
and 1FFH is written into the input shift register. Resetting the divided-by-16 counter aligns its roll-overs with the
boundaries of the incoming bit times.
The 16 states of the counter divide each bit time into 16ths. At the 7th, 8th and 9th counter states of each bit time,
the bit detector samples the value of RXD. The value accepted is the value that was seen in at least 2 of the 3
samples. This is done to reject noise. In order to reject false bits, if the value accepted during the first bit time is
not a 0, the receive circuits are reset and the unit continues looking for another 1-to-0 transition. This is to provide
rejection of false start bits. If the start bit is valid, it is shifted into the input shift register, and reception of the rest
of the frame proceeds.
As data bits come in from the right, “1”s shift out to the left. When the start bit arrives at the left most position
in the shift register,(which is a 9-bit register in Mode 1), it flags the RX Control block to do one last shift, load
SBUF and RB8, and set RI. The signal to load SBUF and RB8 and to set RI is generated if, and only if, the
following conditions are met at the time the final shift pulse is generated.
1) RI=0 and
2) Either SM2=0, or the received stop bit = 1
If either of these two conditions is not met, the received frame is irretrievably lost. If both conditions are met, the
stop bit goes into RB8, the 8 data bits go into SBUF, and RI is activated. At this time, whether or not the above
conditions are met, the unit continues looking for a 1-to-0 transition in RXD.
STC MCU Limited 55

8051 INTERNAL BUS
TB8
Timer 1 WRITE
Overflow TO
DS Q SBUF
SBUF TXD
CL
÷2 ZERO DETECTOR
SMOD SMOD
=0 =1
START SHIFT DATA
TX CONTROL
÷16 TX CLOCK TI SEND
SERIAL
PORT
INTERRUPT
÷16
SAMPLE
1-TO-0 RX CLOCK RI LOAD
TRANSITION START SBUF
DETECTOR RX CONTROL SHIFT
1FFH
BIT
DETECTOR
INPUT SHIFT REG.
RXD (9 BITS)
LOAD SHIFT
SBUF
SBUF
READ
SBUF
8051 INTERNAL BUS
TX
CLOCK
WRITE TO SBUF
SEND
DATA TRANSMIT
SHIFT
TXD D0 D1 D2 D3 D4 D5 D6 D7 STOP BIT
TI START BIT
RX CLOCK
RXD D1 D2 D3 D4 D5 D6 D7
START BIT D0 STOP BIT
RECEIVE BIT DETECTOR SAMPLE TIMES
SHIFT
RI
Serial Port Mode 1

STC MCU Limited. 56
Mode 2
11 bits are transmitted through TXD or received through RXD. The frame data includes a start bit(0), 8 data
bits, a programmable 9th data bit and a stop bit(1). On transmit, the 9th data bit comes from TB8 in SCON. On
receive, the 9th data bit goes into RB8 in SCON. The baud rate is programmable to either 1/32 or 1/64 the System
clock cycle.
Baud rate in mode 2 = (2SMOD/64) x SYSclk
Transmission is initiated by any instruction that uses SBUF as a destination register. The “write to SBUF”
signal also loads TB8 into the 9th bit position of the transmit shift register and flags the TX Control unit that a
transmission is requested. Transmission actually happens at the next rollover of divided-by-16 counter. Thus the
bit times are synchronized to the divided-by-16 counter, not to the “write to SBUF” signal.
The transmission begins when /SEND is activated, which puts the start bit at TXD. One bit time later, DATA is
activated, which enables the output bit of the transmit shift register to TXD. The first shift pulse occurs one bit
time after that. The first shift clocks a “1”(the stop bit) into the 9th bit position on the shift register. Thereafter,
only “0”s are clocked in. As data bits shift out to the right, “0”s are clocked in from the left. When TB8 of the data
byte is at the output position of the shift register, then the stop bit is just to the left of TB8, and all positions to the
left of that contains “0”s. This condition flags the TX Control unit to do one last shift, then deactivate /SEND and
set TI. This occurs at the 11th divided-by-16 rollover after “write to SBUF”.
Reception is initiated by a 1-to-0 transition detected at RXD. For this purpose, RXD is sampled at a rate of
16 times whatever baud rate has been estabished. When a transition is detected, the divided-by-16 counter is
immediately reset, and 1FFH is written into the input shift register.
At the 7th, 8th and 9th counter states of each bit time, the bit detector samples the value of RXD. The value accepted
is the value that was seen in at least 2 of the 3 samples. This is done to reject noise. In order to reject false bits, if
the value accepted during the first bit time is not a 0, the receive circuits are reset and the unit continues looking
for another 1-to-0 transition. If the start bit is valid, it is shifted into the input shift register, and reception of the
rest of the frame proceeds.
As data bits come in from the right, “1”s shift out to the left. When the start bit arrives at the leftmost position
in the shift register,(which is a 9-bit register in Mode-2 and 3), it flags the RX Control block to do one last shift,
load SBUF and RB8, and set RI. The signal to load SBUF and RB8 and to set RI is generated if, and only if, the
following conditions are met at the time the final shift pulse is generated.:
1) RI=0 and
2) Either SM2=0, or the received 9th data bit = 1
If either of these two conditions is not met, the received frame is irretrievably lost. If both conditions are met,
the stop bit goes into RB8, the first 8 data bits go into SBUF, and RI is activated. At this time, whether or not the
above conditions are met, the unit continues looking for a 1-to-0 transition at the RXD input.
Note that the value of received stop bit is irrelevant to SBUF, RB8 or RI.
STC MCU Limited 57

8051 INTERNAL BUS
TB8
WRITE
TO
SBUF DS Q SBUF TXD
CL
ZERO DETECTOR
SYSclk/2
STOP BIT SHIFT DATA
START GEN.
MODE 2 TX CONTROL
SMOD=1 SERIAL
PORT
÷2 INTERRUPT
SMOD=0
÷16
(SMOD IS PCON.7) SAMPLE
1-TO-0 RX RI LOAD
TRANSITION CLOCK SBUF
START
1FFH
BIT
DETECTOR
INPUT SHIFT REG.
RXD (9 BITS)
LOAD SHIFT
SBUF
SBUF
READ
SBUF
8051 INTERNAL BUS

TX
CLOCK
WRITE TO SBUF
SEND
DATA S1P1 TRANSMIT
SHIFT
TXD D0 D1 D2 D3 D4 D5 D6 D7 TB8 STOP BIT
TI START BIT
STOP BIT GEN
RX CLOCK
RXD D1 D2 D3 D4 D5 D6 RB8
START BIT D0 D7 STOP BIT
RECEIVE
BIT DETECTOR SAMPLE TIMES
SHIFT
RI
Serial Port Mode 2

STC MCU Limited. 58
Mode 3
Mode 3 is the same as mode 2 except the baud rate is variable.
Baud rate in mode 3 = (2SMOD /32 ) x timer 1overflow rate ( if AUXR.0/S1BRS=0 )

In all four modes, transmission is initiated by any instruction that use SBUF as a destination register. Reception
is initiated in mode 0 by the condition RI = 0 and REN = 1. Reception is initiated in the other modes by the
incoming start bit with 1-to-0 transition if REN=1.
8.2 Frame Error Detection
When used for frame error detect, the UART looks for missing stop bits in the communication. A missing bit will
set the FE bit in the SCON register. The FE bit shares the SCON.7 bit with SM0 and the function of SCON.7 is
determined by PCON.6(SMOD0). If SMOD0 is set then SCON.7 functions as FE. SCON.7 functions as SM0
when SMOD0 is cleared. When used as FE, SCON.7 can only be cleared by software.
8.3 Multiprocessor Communications
Modes 2 and 3 have a special provision for multiproceasor communications. In these modes 9 data bits are
received.The 9th one goes into RB8. Then comes a stop bit. The port can be programmed such that when the stop
bit is received,the serial port interrupt will be activated only if RB8 = 1. This feature is enabled by setting bit
SM2 in SCON. A way to use this feature in multiprocessor systems is as follows.
When the master processor wants to transmit a block of data to one of several slaves, it first sends out an address
byte which identifies the target slave.An address byte differs from a data byte in that the 9th bit is 1 in an address
byte and 0 in a data byte.With SM2 = 1, no slave will be interrupted by a data byte. An address byte, however,will
interrupt all slaves, so that each slave can examine the received byte and see if it is being addressed.The addressed
slave will clear its SM2 bit and prepare to receive the data bytes that will be coming. The slaves that weren’t be-
ing addressed leave their SM2s set and go on about their business, ignoring the coming data bytes.
SM2 has no effect in Mode 0,and in Mode 1 can be used to check the validity of the stop bit. In a Mode 1 recep-
tion, if SM2 = 1, the receive interrupt will not be activated unless a vatid stop bit is received.
STC MCU Limited 59

8051 INTERNAL BUS
TB8
TIMER 1 WRITE
OVERFLOW TO
DS Q SBUF
SBUF TXD
CL
÷2 ZERO DETECTOR
SMOD SMOD
=0 =1
START SHIFT DATA
TX CONTROL
SERIAL
PORT
INTERRUPT
÷16
SAMPLE
1-TO-0 RX CLOCK RI LOAD
TRANSITION START SBUF
1FFH
BIT
DETECTOR
INPUT SHIFT REG.
RXD (9 BITS)
LOAD SHIFT
SBUF
SBUF
READ
SBUF
8051 INTERNAL BUS
TX
CLOCK
WRITE TO SBUF
SEND
DATA TRANSMIT
SHIFT
TXD D0 D1 D2 D3 D4 D5 D6 D7 TB8 STOP BIT
TI START BIT
STOP BIT GEN

RX CLOCK ÷16 RESET
RXD D1 D2 D3 D4 D5 D6 RB8
START BIT D0 D7 STOP BIT
RECEIVE
BIT DETECTOR SAMPLE TIMES
SHIFT
RI
Serial Port Mode 3
STC MCU Limited. 60
8.4 Automatic Address Recognition
Automatic Address Recognition is a future which allows the UART to recognize certain addresses in the serial
bit stream by using hardware to make the comparisons. This feature saves a great deal of software overhead by
eliminating the need for the software to examine every serial address which passes by the serial port. This feature
is enabled by setting the SM2 bit in SCON. In the 9-bit UART modes, Mode 2 and Mode 3, the Receive interrupt
flag(RI) will be automatically set when the received byte contains either the “Given” address or the “Broadcast”
address. The 9-bit mode requires that the 9th information bit is a “1” to indicate that the received information is an
address and not data.
The 8-bit mode is called Mode 1. In this mode the RI flag will be set if SM2 is enabled and the information
received has a valid stop bit following the 8 address bits and the information is either a Given or Broadcast
address.
Mode 0 is the Shift Register mode and SM2 is ignored.
Using the Automatic Address Recognition feature allows a master to selectively communicate with one or more
slaves by invoking the given slave address or addresses. All of the slaves may be contacted by using the broadcast
address. Two special function registers are used to define the slave’s address, SADDR, and the address mask,
SADEN. SADEN is used to define which bits in the SADDR are to be used and which bits are “don’t care”. The
SADEN mask can be logically ANDed with the SADDR to create the “Given” address which the master will
use for addressing each of the slaves. Use of the Given address allows multiple slaves to be recognized which
excluding others. The following examples will help to show the versatility of this scheme :
Slave 0 SADDR = 1100 0000

SADEN = 1111 1101
GIVEN = 1100 00x0

SADEN = 1111 1110
GIVEN = 1100 000x
In the previous example SADDR is the same and the SADEN data is used to differentiate between the two slaves.
Slave 0 requires a “0” in bit 0 and it ignores bit 1. Slave 1 requires a “0” in bit 1 and bit 0 is ignored. A unique
address for slave 0 would be 11000010 since slave 1 requires a “0” in bit 1. A unique address for slave 1 would
be 11000001 since a “1” in bit 0 will exclude slave 0. Both slaves can be selected at the same time by an address
which has bit 0=0 (for slave 0) and bit 1 =0 (for salve 1). Thus, both could be addressed with 11000000.
STC MCU Limited 61

In a more complex system the following could be used to select slaves 1 and 2 while excluding slave 0:

SADEN = 1111 1001
GIVEN = 1100 0xx0

SADEN = 1111 1010
GIVEN = 1110 0x0x

SADEN = 1111 1100
GIVEN = 1110 00xx
In the above example the differentiation among the 3 slaves is in the lower 3 address bits.Slave 0 requires that
bit0 = 0 and it can be uniquely addressed by 11100110. Slave 1 requires that bit 1=0 and it can be uniquely
addressed by 11100101. Slave 2 requires that bit 2=0 and its unique address is 11100011. To select Salve 0 and 1
and exclude Slave 2, use address 11100100, since it is necessary to make bit2=1 to exclude Slave 2.
The Broadcast Address for each slave is created by taking the logic OR of SADDR and SADEN. Zeros in this
result are trended as don’t cares. In most cares, interpreting the don’t cares as ones, the broadcast address will be
FF hexadecimal.
Upon reset SADDR and SADEN are loaded with “0”s. This produces a given address of all “don’t cares as well
as a Broadcast address of all “don’t cares”. This effectively disables the Automatic Addressing mode and allows
the microcontroller to use standard 80C51-type UART drivers which do not make use of this feature.
8.5 Buad Rates

The baud rate in Mode 0 is fixed:
SYSclk
Mode 0 Baud Rate = when AUXR.5/UART_M0x6 =0
12
SYSclk
or = when AUXR.5/UART_M0x6 =1
2
The baud rate in Mode 2 depends on the value of bit SMOD in Special Function Register PCON. If SMOD =0
(which is the value on reset), the baud rate 1/64 the System clock cycle. If SMOD = 1, the baud rate is 1/32 the
System clock cycle .
2SMOD
Mode 2 Baud Rate = ×��
(SYSclk)
64
In the STC11F60XE, the baud rates in Modes 1 and 3 are determined by Timer1 or BRT overflow rate.
The baud rate in Mode 1 and 3 are fixed:
Mode 1,3 Baud rate = (2SMOD /32 ) x timer 1 overflow rate ( if AUXR.0/S1BRS=0 )
Timer 1 overflow rate = (SYSclk/12)/(256 - TH1);

BRT overflow rate = (SYSclk/2) / (256 –BRT), when AUXR.2/BRTx12=1
or = (SYSclk/2/12) / (256 – BRT) , when AUXR.2/BRTx12=0
STC MCU Limited. 62
When Timer 1 is used as the baud rate generator, the Timer 1 interrupt should be disabled in this application.
The Timer itself can be configured for either “timer” or “cormter” operation, and in any of its 3 running modes.
In the most typcial applications, it is configured for “timer” operation, in the auto-reload mode (high nibble of
TMOD = 0010B).
One can achieve very low baud rate with Timer 1 by leaving the Timer 1 interrupt enabled, and configuring the
Timer to run as a 16-bit timer (high nibble of TMOD = 0001B), and using the Timer 1 interrupt to do a l6-bit
software reload.
The following figure lists various commonly used baud rates and how they can be obtained from Timer 1.
Timer 1
Baud Rate SYSclk SMOD Reload
C/T Mode
Value
Mode 0 MAX:1MHZ 12MHZ X X X X
Mode 2 MAX:375K 12MHZ 1 X X X
Mode 1,3:62.5K 12MHZ 1 0 2 FFH
19.2K 11.059MHZ 1 0 2 FDH
9.6K 11.059MHZ 0 0 2 FDH
4.8K 11.059MHZ 0 0 2 FAH
2.4K 11.059MHZ 0 0 2 F4H
1.2K 11.059MHZ 0 0 2 E8H
137.5 11.986MHZ 0 0 2 1DH
110 6MHZ 0 0 2 72H
110 12MHZ 0 0 1 FEEBH
Timer 1 Generated Commonly Used Baud Rates
STC MCU Limited 63

Chapter 9 IAP / EEPROM
The ISP in STC11Fxx/10xx series makes it possible to update the user’s application program and non-volatile
application data (in IAP-memory) without removing the MCU chip from the actual end product. This useful
capability makes a wide range of field-update applications possible. (Note ISP needs the loader program pre-
programmed in the ISP-memory.) In general, the user needn’t know how ISP operates because STC has provided
the standard ISP tool and embedded ISP code in STC shipped samples.
IAP / ISP Control Register
The following special function registers are related to the IAP/ISP operation. All these registers can be
accessed by software in the user’s application program.
Value after
MSB LSB Reset
ISP/IAP Flash Data
IAP_DATA C2H 1111 1111B
Register
ISP/IAP Flash
IAP_ADDRH C3H 0000 0000B
Address High
ISP/IAP Flash
IAP_ADDRL C4H 0000 0000B
Address Low
ISP/IAP Flash - - - - - - MS1 MS0
IAP_CMD C5H xxxx x000B
Command Register
ISP/IAP Flash
IAP_TRIG C6H xxxx xxxxB
Command Trigger
ISP/IAP Control IAPEN SWBS SWRST CMD_FAIL - WT2 WT1 WT0
IAP_CONTR C7H 0000 x000B
Register
STC MCU Limited. 64

IAP_DATA: ISP/IAP Flash Data Register
LSB
name
IAP_DATA is the data port register for ISP/IAP operation. The data in IAP_DATA will be written into
the desired address in operating ISP/IAP write and it is the data window of readout in operating ISP/
IAP read.
IAP_ADDRH: ISP/IAP Flash Address High

LSB
name
IAP_ADDRH is the high-byte address port for all ISP/IAP modes.
IAP_ADDRL: ISP/IAP Flash Address Low

LSB
name
IAP_ADDRL is the low port for all ISP/IAP modes. In page erase operation, it is ignored.
IAP_CMD: ISP/IAP Flash Command Register

LSB
name - - - - - - MS1 MS0
B7~B2: Reserved.
MS1, MS0 : ISP/IAP operating mode selection. IAP_CMD is used to select the flash mode for
performing numerous ISP/IAP function or used to access protected SFRs.
0, 0 : Standby
0, 1 : Data Flash/EEPROM read.
1, 0 : Data Flash/EEPROM program.
1, 1 : Data Flash/EEPROM page erase.
IAP_TRIG: ISP/IAP Flash Command Trigger.

LSB
name
IAP_TRIG is the command port for triggering ISP/IAP activity and protected SFRs access. If IAP_TRIG is filled
with sequential 0x5Ah, 0xA5h and if IAPEN(IAP_CONTR.7) = 1, ISP/IAP activity or protected SFRs access will
triggered.
STC MCU Limited 65

IAP_CONTR: ISP/IAP Control Register
LSB
name IAPEN SWBS SWRST CMD_FAIL - WT2 WT1 WT0
IAPEN : ISP/IAP operation enable.
0 : Global disable all ISP/IAP program/erase/read function.
1 : Enable ISP/IAP program/erase/read function.
SWBS: software boot selection control.
0 : Boot from main-memory after reset.
1 : Boot from ISP memory after reset.
SWRST: software reset trigger control.
0 : No operation
1 : Generate software system reset. It will be cleared by hardware automatically.
CMD_FAIL: Command Fail indication for ISP/IAP operation.
0 : The last ISP/IAP command has finished successfully.
1 : The last ISP/IAP command fails. It could be caused since the access of flash memory was inhibited.
B3: Reserved. Software must write “0” on this bit when IAP_CONTR is written.
WT2~WT0 : ISP/IAP programming clock source selection.
Setting wait times CPU wait times
Program Sector Erase Recommended System
WT2 WT1 WT0 Read
<=55uS <=21mS Clock Frequency (MHz)
1 1 1 2 SYSclks 55 SYSclks 21012 SYSclks < 1MHz
STC MCU Limited. 66

STC11Fxx / STC11Lxx series MCU internal EEPROM Selection Table
EEPROM Sector Begin_Sector End_Sector
Type
(Byte) Numbers Begin_Address Ene_Address
STC11F01E/STC11L01E 2K 4 0000H 0FFFH
STC11F04E/STC11L04E 1K 2 0000H 3FFH
STC11F05E/STC11L05E 1K 2 0000H 3FFH
Type
STC11F08XE/STC11L08XE 32K 64 0000H 7FFFH
STC11F16XE/STC11L16XE 32K 64 0000H 7FFFH
STC11F20XE/STC11L20XE 29K 58 0000H 73FFH
Type
STC10F10XE/STC10L10XE 3K 6 0000H 0BFFH
STC MCU Limited 67

Chapter 10 STC10/11 xx series Selection Table
E External Special
S T E Internal
F interrupts timer Package Package
Type U Internal Reset
Operating l A I PCA/ W P which for of of
1T 8051 a A A/ low threshold
voltage s R M PWM D R can wake waking 40-pin 44-pin
MCU R D voltage voltage
(V) h M E D/A T O up power power (36 I/O (40 I/O
(B) T interrupt can be down down ports) ports)
(B) R M configured
(B) mode mode
LQFP/
STC10F04 5.5~3.3 4K 256 2 1-2 N N Y N Y Y 5 N PDIP
PLCC
LQFP/
STC10F04XE 5.5~3.3 4K 512 2 1-2 N N Y 5K Y Y 5 N PDIP
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
STC10F14X 5.5~3.7 14K 512 2 1-2 N N Y IAP Y Y 5 N PDIP
PLCC
LQFP/
STC10L04 3.6~2.1 4K 256 2 1-2 N N Y N Y Y 5 N PDIP
PLCC
LQFP/
STC10L04XE 3.6~2.1 4K 512 2 1-2 N N Y 5K Y Y 5 N PDIP
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
STC10L14X 3.6~2.4 14K 512 2 1-2 N N Y IAP Y Y 5 N PDIP
PLCC
STC MCU Limited. 68
E External
S T E Internal Special
F interrupts Package Package
Type l U Internal Reset timer for
A I PCA/ W P which of of
1T 8051 Operating a A A/ low threshold waking
R M PWM D R can wake 40-pin 44-pin
MCU voltage (V) s R D voltage voltage power
h M E D/A T O up power (36 I/O (40 I/O
(B) T interrupt can be down
down
ports) ports)
(B) R M configured mode
(B) mode
LQFP/
STC11F16XE 5.5~3.7 16K 1280 2 1-2 N N Y 45K Y Y 5 Y PDIP
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
IAP11F62XE 5.5~4.1 62K 1280 2 1-2 N N Y IAP Y Y 5 Y PDIP
PLCC
LQFP/
PLCC
LQFP/
STC11L16XE 3.6~2.1 16K 1280 2 1-2 N N Y 45K Y Y 5 Y PDIP
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
PLCC
LQFP/
IAP11L62XE 3.6~2.4 62K 1280 2 1-2 N N Y IAP Y Y 5 Y PDIP
PLCC
LQFP/
PLCC
STC MCU Limited 69

STC11F/10Fxx Series MCU STC11L/10Lxx Series MCU Data Sheet

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STC11F/10Fxx series MCU

STC11L/10Lxx series MCU

STC MCU Limited 1

STC MCU Limited. 4

AUX-RAM RAM ADDR

B Register ACC Stack FLASH

TMP2 TMP1 Timer 0/1 ISP/IAP

Control Port 0,1,2,3,4

STC11/10Fxx Block Diagram

STC MCU Limited 5

STC MCU Limited. 6

STC MCU Limited 7

L 0.45 0.60 0.75

STC MCU Limited. 8

STC MCU Limited 9

Seating Plane DIMENSIONS IN

3.DIMENSIONS E AND D D0 NOT INCLUDE MODE

4.DIMENSION b1 DOES NOT INCLUDE DAMBAR

STC MCU Limited. 10

CLK_DIV register (Clock Divider)

2.2.1 Idle Mode

2.2.2 Slow Down Mode

STC MCU Limited. 12

2.3 RESET Control

2.3.1 Reset pin

2.3.2 Power-On Reset (POR)

WDT_CONTR: Watch-Dog-Timer Control Register

WDT_FLAG : WDT reset flag.

STC MCU Limited 13

IAP_CONTR: ISP/IAP Control Register

2.3.5 MAX810 power-on-reset delay

STC MCU Limited. 14

60K Special Function

STC MCU Limited 15

3.2.2 Auxiliary RAM

3.2.3 External RAM

3.2.4 Special Function Register for RAM

STC MCU Limited. 16

STC MCU Limited 17

Auxiliary RAM 1KB

GF2 : General Flag. It can be used by software.

DPS : DPTR registers select bit.

STC MCU Limited. 18

{ALES1 and ALES0} :

Timing diagram for MOVX @DPTR, A without stretch

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P2 High-byte address High-byte address

Timing diagram for MOVX @DPTR, A with stretch {RWS2,RWS1,RWS0} = 3’b111

P0 Low-byte Address Data for writing

/RD Trd = (1+7) cycles

MOVX read cycle

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4.1.1 Quasi-bidirectional I/O

Vcc Vcc Vcc

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Table: Configuration of I/O port mode.

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