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    Interrupt - MCS51

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    Setyawan Ajie Sukarno
    The document discusses interrupts in microcontrollers. It defines interrupts as events that cause the main program to temporarily stop executing so that an interrupt service routine can run. Interrupts provide advantages over polling by allowing the CPU to remain free until an interrupt occurs. The document describes different types of interrupts in MCS-51 microcontrollers including external, timer, and serial interrupts. It provides details on interrupt registers, vectors, and examples of implementing external interrupts to display messages or change program flow.

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    Interrupt - MCS51

    Uploaded by

    Setyawan Ajie Sukarno
    99 views18 pages
    The document discusses interrupts in microcontrollers. It defines interrupts as events that cause the main program to temporarily stop executing so that an interrupt service routine can run. Interrupts provide advantages over polling by allowing the CPU to remain free until an interrupt occurs. The document describes different types of interrupts in MCS-51 microcontrollers including external, timer, and serial interrupts. It provides details on interrupt registers, vectors, and examples of implementing external interrupts to display messages or change program flow.

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    The document discusses interrupts in microcontrollers. It defines interrupts as events that cause the main program to temporarily stop executing so that an interrupt service routine can run. Interrupts provide advantages over polling by allowing the CPU to remain free until an interrupt occurs. The document describes different types of interrupts in MCS-51 microcontrollers including external, timer, and serial interrupts. It provides details on interrupt registers, vectors, and examples of implementing external interrupts to display messages or change program flow.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    99 views18 pages

    Interrupt - MCS51

    Uploaded by

    Setyawan Ajie Sukarno
    The document discusses interrupts in microcontrollers. It defines interrupts as events that cause the main program to temporarily stop executing so that an interrupt service routine can run. Interrupts provide advantages over polling by allowing the CPU to remain free until an interrupt occurs. The document describes different types of interrupts in MCS-51 microcontrollers including external, timer, and serial interrupts. It provides details on interrupt registers, vectors, and examples of implementing external interrupts to display messages or change program flow.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    of 18

    INTERRUPT

    Setyawan Ajie Sukarno


    Introduction
     Interrupt is an event that cause main program
    temporary stopped to execute the other program
    (interrupt service routine)
     2 ways to make a hardware interface
     polling/scanning, and
     interrupt
    Polling vs Interrupt
     Polling :
     CPU check the device frequently, waiting for
    “service flag”
     CPU always busy for doing polling request
     Interrupt :
     The device will sent an interrupt signal when it
    ready or need to interrupt CPU
     CPU always “free” when interrupt service is off
    Interrupt in Fields
     Keyboard on Desktop PC and Notebook
     Emergency Button
     Thermal Sensor in Chiller Machine
     Load Sensor in Elevator
     Cancel Button in ATM
    Events associated to interrupts

     External port lines


     Level and edge triggered
     Peripherals
     Serial I/O
     Asynchronous
     I2C, SPI
     Timers time-out
     A/D end of conversion
     Software instruction
    Interrupt’s SFR
     Interrupt Enable (IE)

    EA - ET2 ES ET1 EX1 ET0 EX0


    Interrupt’s SFR
     Interrupt Priority (IP)

    - - PT2 PS PT1 PX1 PT0 PX0


    Types of Interrupt
     There are 3 types of interrupt in MCS-51 family :
     External Interrupt
     Timer Interrupt
     Serial Interrupt
    External Interrupt
     There are 2 types of external interrupt in MCS-51
    family :
     EXT0
     EXT1
    External Interrupt
     External Interrupt 0 (EXT0)
     Pin 12 (P3.2)
     Active Low
     External Interrupt 1 (EXT1)
     Pin 13 (P3.3)
     Active Low
    External Interrupt
     Initialization
     IE (Interrupt Enable)
     Pin 7 : EA (Enable All)
     Pin 0 : EX0 (Enable External Int 0)
     Pin 2 : EX1 (Enable Ext Int 1)

    setb ea
    setb exo
    setb ex1
    External Interrupt
     Initialization
     IP (Interrupt Priority)
     Pin 0 : PX0 (Priority on Ext Int 0)
     Pin 2 : PX1 (Priority on Ext Int 1)

    setb px0
    setb px1
    External Interrupt
     Interrupt Vector
     When the interrupt signal detected, microcontroller
    will stop the program that is running, and execute
    the program in the interrupt vector
     Place (memory) where the Interrupt Service
    Routine are stored
    External Interrupt
     Interrupt Vector
     EXT0 03h
     EXT1 13h
     ET0 0bh
     ET1 1bh
     ES 23h

    org 03h
    ……… // write your program here
    reti
    External Interrupt
     Interrupt Vector

    org 03h
    lcall isr_ext0
    reti
    ...
    org 100h
    isr_ext0:
    ……… // write your program here
    ret
    External Interrupt

    ANY QUESTION ???


    Assignments #1
    Make an interrupt programm, when:
    1. Interrupt signal is not detected, the
    microcontroller will execute an up-counter from
    00-99 which will be displayed in 7 segments.
    2. Interrupt signal detected, the microcontroller will
    display “intd” in 7 segments.
    Assignments #2
    Make an interrupt programm, when:
    1. Interrupt signal is not detected, the
    microcontroller will execute an up-counter from
    00-99 which will be displayed in LCD.
    2. Interrupt signal detected, the microcontroller will
    display “programm interrupted” in LCD screen.

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