JPH0522774A - Data receiver for compact electric device using battery and communication method - Google Patents

Abstract

PURPOSE:To enable a data receiving to restart clock oscillation without using a signal other than data signal even when a clock for receiving is in stop and to receive successive asynchronous serial data. CONSTITUTION:Clock generating section 4 generates a clock for receiving an asynchronous serial data signal, and an asynchronous serial data receiving section 7 receives an asynchronous serial data signal in response to the generation of the receiving purpose clock. Further, with the state that clock stop section 5 stops clock oscillation and that clock oscillation restart section 6 stops clock oscillation, in response to the change of serial data signal the clock oscillation is restarted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to communication between individual unit devices in a battery-powered small device such as a photographing device comprising a combination of unit devices such as a camera, a lens, a motor drive, an electric pan head, and a remote controller. Or, relating to communication between the above-mentioned small equipment and a general-purpose communication device such as a personal computer, especially asynchronous serial data communication (communication of asynchronous clock) without communication of synchronization clock.
And a data communication method.

[0002]

2. Description of the Related Art A method for performing asynchronous serial data communication is described in "Electronic Life, July 1990", a magazine of the Japan Broadcasting Corporation.
It does not mention the technology that uses the asynchronous serial data communication for the shooting device).

Generally, asynchronous serial data communication is a method of transmitting or receiving serial data based on independent clocks on the transmitting side and the receiving side without performing communication of a clock signal for synchronization.

The clock cycle at the time of transmission or reception is called a baud rate. Before communication, the baud rate is made the same on the transmitting side and the receiving side, and the first of the asynchronous serial data. By adding a signal called a start bit, which indicates the start of data, and a signal called a stop bit, which indicates the end of data, to the data signal, serial data communication is possible without a clock for synchronization.

[0005]

However, in the asynchronous serial data communication, each of the transmitting side and the receiving side must have an independent clock, and especially when the receiving side receives serial data. Since it cannot be predicted, it is necessary to constantly oscillate the clock.

On the other hand, a small device such as a photographing device is usually controlled by a battery, and the communication control naturally uses the battery as a power source. Therefore, when a small device such as the photographing device tries to receive the asynchronous serial data, the clock must be constantly oscillated, which causes a problem that the battery is exhausted in a short period of time.

If data transmission is started by a signal other than the asynchronous serial data signal, it is not necessary for the receiving side to constantly oscillate the clock, but there is a problem that the number of signal lines increases. Occurs.

In view of the above problems, the present invention provides a signal line other than the data signal line in a small device such as a photographing device for receiving asynchronous serial data even when the reception clock is stopped. The purpose is to restart the oscillation of the clock without using, and enable reception of the serial data thereafter.

[0009]

In order to achieve the above object, a data receiving apparatus of a battery-powered small-sized device according to a first aspect uses a battery which receives an asynchronous serial data signal and performs control based on the received data. In a small device, clock generation means for generating a reception clock for the asynchronous serial data signal, reception means for receiving the asynchronous serial data signal in response to the reception clock, and oscillation of the reception clock And a clock oscillation resuming means for restarting the oscillation of the receiving clock in response to a signal change of the serial data signal while the oscillation of the receiving clock is stopped. And The data receiving device for a battery-powered small device according to the second aspect permits the receiving means to receive the asynchronous serial data after a predetermined time elapses after the oscillation of the reception clock is restarted, and receives the asynchronous serial data. It is characterized in that serial data is not received after the restart of the clock oscillation for use. Further, in the data communication method for a battery-powered small device according to the third aspect, in response to the change in the asynchronous serial data signal, the oscillation of the clock for data reception is restarted from the stopped state to the oscillated state, and the oscillation is restarted. The data receiving device that employs subsequent serial data as control data restarts the oscillation of the receiving clock, and then the data transmitting device transmits dummy data unrelated to the control data.

[0010]

That is, in the data receiving device for a battery-powered small device according to the first aspect of the present invention, a clock is generated in the battery-powered small device that receives data of an asynchronous serial data signal and performs control based on the received data. Means generates a clock for receiving the asynchronous serial data signal,
The receiving means receives the asynchronous serial data signal in response to the receiving clock, the clock stopping means stops the oscillation of the receiving clock, and the clock oscillation restarting means stops the oscillation of the receiving clock. In this state, the oscillation of the receiving clock is restarted in response to the signal change of the serial data signal. Further, in the data receiving device for a battery-powered small device according to the second aspect, the receiving means is allowed to receive the asynchronous serial data after a predetermined time has elapsed after the oscillation of the receiving clock is restarted, No data is received after the oscillation is restarted. Further, in the data communication method for a battery-powered small device according to the third aspect, in response to the change of the asynchronous serial data signal, the oscillation of the clock for data reception is restarted from the stopped state to the oscillated state, and the oscillation is restarted. A data receiving device that employs the asynchronous serial data after that as control data,
The data transmission device that transmits the asynchronous serial data to the reception device performs communication, and after the data reception device restarts the oscillation of the reception clock, the data transmission device transmits dummy data unrelated to the control data. Send.
Therefore, in an imaging device that receives asynchronous serial data, even if the reception clock is stopped, the oscillation of the reception clock is restarted without using the data signal, and the serial data after that is restarted. Can be received.

[0011]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing the configuration of a small battery-using device according to the first embodiment of the present invention.

In the figure, 1 is an asynchronous serial data receiving device, 2 is an asynchronous serial data transmitting device, 3 is a serial data receiving terminal, 4 is a clock generating part, 5 is a clock stopping part, and 6 is a clock oscillation restart. Reference numeral 7 is an asynchronous serial data receiver, and 8 is a controller.

Here, the asynchronous serial data receiving apparatus 1 is a small battery-using device such as a photographing device including a combination of unit devices such as a camera, a strobe, a lens, a motor drive, an electric platform, and a remote controller. The serial data reception terminal 3 receives the serial data from the asynchronous serial data transmission device 2.

The asynchronous serial data transmitter 2 comprises a unit device in the photographing device or a general-purpose transmitter having a serial data transmitter such as a personal computer.

That is, for example, when the camera receives serial data from the lens, the camera corresponds to the receiving device 1 and the lens corresponds to the transmitting device 2, and when the lens receives serial data from the personal computer, the lens Corresponds to the receiving device 1, and the personal computer corresponds to the transmitting device 2. The clock generator 4 stops the clock in response to the signal from the clock stop unit 5 and restarts the clock oscillation in response to the signal from the clock oscillation restart unit 6. That is, the clock stop unit 5 detects the elapse of the predetermined time and stops the clock when serial data is not received for the predetermined time, for example.

It should be noted that the serial data signal (hereinafter, SA) from the transmitting device 2 is input to both the serial data receiving unit 7 and the clock oscillation resuming unit 6 so that two serial signals are received inside the receiving device 1. Data signal (SA1 and SA
The clock oscillation restarting unit 6 restarts the clock in accordance with SA2.

In this way, the asynchronous serial data receiving unit 7 receives the SA1 in response to the clock signal from the clock generating unit 4, and the control unit 8 controls the SA1 received by the asynchronous serial data receiving unit 7. Based on the data, for example, exposure control, lens driving, and other photographing control are performed.
Hereinafter, with reference to the timing chart of FIG. 2, the operation of each part of the small battery-using device of the embodiment will be described.

Here, SA is the serial data receiving terminal 3
The serial data signal input from the transmitter 2 is received by SB, the clock oscillation restart signal is received by SC, the clock stop signal is received by SC, the receiving clock is received by SD, and the asynchronous serial data receiving unit 7 receives SE. Each represents serial data. Now, it is assumed that serial data is transmitted from the transmission device 2 with the clock stopped.

First, in response to the start bit (DST) of the first SA data (dummy data), the SB signal (clock oscillation restart signal) is generated by the clock oscillation restart unit 6. Then, in response to the SB signal, the clock is restarted from the clock generator 4 as in SD1.

Further, the asynchronous serial data receiving section 7 prepares for reception between the data section (DDT) of the dummy data of SA and the stop bit (DSP), and the start bit (control data) of the next data (control data) Wait for SST).

Then, in response to the start bit (SST) of the control data, the asynchronous serial data receiving section 7 starts receiving serial data, and the control data is synchronized with the rising edge of the clock signal (SD). (SDT)
To receive. Then, the stop bit (SSP) of the control data is detected and the reception of the 1-byte serial data is completed.

After the end of the data reception, when there is no reception for a predetermined time, the clock stop unit generates SC, and when the clock stop signal (SC) is generated, the clock is stopped in SD in SD 2 in response thereto. . FIG. 3 shows a data receiving device 1 having a microprocessor (hereinafter, CPU).
It is a block diagram which shows the structure of the 2nd Example of this invention at the time of using.

Here, as shown in FIG. 3, the clock generating section 4, the clock stopping section 5, the clock oscillation restarting section 6,
Each unit of the asynchronous serial data receiving unit 7 and the control unit 8 can be built in the general CPU 31, but a general microprocessor cannot receive asynchronous serial data when the clock is stopped. Therefore, in this embodiment, the serial data receiving terminal 3 is connected to the serial data input terminal (RXD) and the interrupt input terminal (IN of the CPU 31).
T). The actual operation of the second embodiment of the present invention will be described below with reference to the flowchart of FIG.

First, the CPU 31 permits the interrupt input from the interrupt input immediately after the start (reset start) (step S41) and stops the system clock of the CPU (step S42). In this embodiment, the system data clock is used as the serial data reception clock, so the serial data reception is similarly stopped.

When asynchronous serial data is transmitted from the transmitter 2 in this state, an interrupt is generated by the start bit (DST) of the first data (dummy data), and the CPU 31 oscillates the system clock. Resume. Next, the CPU 31 prohibits the interrupt input and works so that the interrupt does not occur in the subsequent asynchronous serial data (step S43). Then, the dummy data (DD
It waits for a predetermined time so that erroneous data is not received from the middle of T) (step S44). After this predetermined time has elapsed, asynchronous serial data (control data) is received (step S45), and control is performed based on the data (step S46). After that, the process returns to step S1 and the operation is repeated.

In the asynchronous serial data receiving apparatus 1 which receives asynchronous serial data using the CPU 31 as described above, the serial data reception signal is sent to the CPU.
Asynchronous serial data can be received from the clock stopped state only by supplying it to the interrupt input terminal 31. Next, FIG. 5 is a block diagram showing a configuration of a data receiving apparatus 1 in a third embodiment of a small battery-using device according to the present invention.

In this embodiment, the serial data receiving terminal 3
Is connected to the serial data input terminal (RXD) of the CPU 51, and is also connected to the reset input terminal (RST) via the reset input enable gate 9. Also, CPU
Reference numeral 51 has a terminal (RE) for controlling the opening and closing of the reset input permission gate 9, and controls the opening and closing of the gate 9. Less than,
The actual operation of the third embodiment of the present invention will be described based on the flowchart of FIG.

First, the CPU 51 opens the reset input permission gate 9 immediately after the start (reset start) to prohibit the reset by the serial data signal (step S6).
1). Since the system clock is oscillating in this state, it is naturally possible to receive asynchronous serial data.

Next, after waiting for a predetermined time (step S6)
2) Receive asynchronous serial data (step S)
63). Then, it is determined whether the received data is dummy data or control data (step S64). If the received data is dummy data, the process returns to step S63. If the data is control data, the process proceeds to step S65.

When the CPU 51 is reset-started by means other than the asynchronous serial data signal such as power-on and the clock is oscillating, the first received data becomes dummy data and the next data is the control data. Therefore, the determination is made in step S64. In the next step S65, control is performed based on the received control data. Next, the reset input permission gate is closed to permit the reset input (step S66), and then the system clock is stopped (step S67).

When asynchronous serial data is transmitted from the transmitter in this state, the CP is generated by the start bit (DST) of the first data (dummy data) of the transmission data.
U51 is reset and the processing from step S61 is performed again. The predetermined time in step 62 is a waiting time for preventing the reception of erroneous data in the middle of dummy data (DDT).

The third embodiment described above does not require the interrupt input terminal as in the second embodiment, and the CPU 51 is reset every time communication is performed, so that the CPU 51 is reset.
It is possible to prevent the malfunction of.

In addition, in the second and third embodiments, a predetermined time is waited after an interrupt input or a reset input so that erroneous data is not received in the middle of dummy data (DDT). Although it takes time, as shown in FIG. 2, data in which all bits are in the same state,
That is, if it is "FFh" or "00h" (h is a symbol representing a hexadecimal number), the data signal does not change in the middle of the dummy data, and the receiving unit 7 can properly judge the start bit of the control data. It is not necessary to perform the waiting time processing.

Further, if the time from the oscillation stop of the CPU 31, 51 to the restart of the oscillation is extremely faster than the baud rate or the baud rate is much slower, it is received during the start bit of the first asynchronous serial data signal. Since the preparation is ready, the transmitting device does not need to transmit the dummy data, and the receiving device side does not need the dummy data waiting time process or the dummy data determining process.

Further, as described above, the present invention is applied to, for example, a camera, a strobe, a lens, a motor drive, an electric pan head,
When applied to an imaging device consisting of a combination of unit devices such as a remote controller, communication between each device unit,
Alternatively, when performing communication between each unit device or the photographing device and a general-purpose communication device such as a personal computer by asynchronous serial data communication, even if there is no signal line other than the serial data signal line, It is possible to restart the oscillation of the receiving clock, so that it is possible to stand by without consuming current, so the battery of the shooting device can be used even when shooting for a long time or when performing remote control. It is possible to prevent consumption. Further, since only one data receiving terminal is required for each unit device, there is no cost and no space is required.

[0036]

According to the present invention, in a data receiving device of a battery-powered small device for receiving asynchronous serial data, from the state where the receiving clock is stopped without using any signal other than the data signal line, The clock oscillation can be restarted and the subsequent serial data can be received.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of a small battery-using device of the present invention.

FIG. 2 is a timing chart showing the operation of each unit in the first embodiment.

FIG. 3 is a block diagram of a data receiving apparatus according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing an actual operation of the second embodiment.

FIG. 5 is a block configuration diagram of a data receiving apparatus according to a third embodiment of the present invention.

FIG. 6 is a flowchart showing an actual operation of the third embodiment.

[Explanation of symbols]

1 ... Receiving device, 2 ... Asynchronous serial data transmitting device,
3 ... Serial data receiving terminal, 4 ... Clock generator, 5
... Clock stop unit, 6 ... Clock oscillation restart unit, 7 ... Asynchronous serial data receiving unit, 8 ... Control unit, 31, 51 ...
CPU.

Claims (3)

[Claims] 1. An asynchronous serial data signal is received,
In a battery-powered small device that performs control based on the received data, a clock generation unit that generates a reception clock of the asynchronous serial data, and a reception unit that receives the asynchronous serial data in response to the reception clock. Clock stopping means for stopping the oscillation of the reception clock, and clock oscillation for restarting the oscillation of the clock in response to a signal change of the asynchronous serial data signal in the state where the oscillation of the reception clock is stopped. A data receiving apparatus for a small battery-powered device, comprising: a restarting unit. 2. The receiving means is configured to stop receiving the serial data immediately after restarting clock oscillation and receive the serial data after a predetermined time has elapsed. Data receiving device for small equipment using batteries. 3. Data reception in which oscillation of a data reception clock is restarted from a stopped state to an oscillation state in response to a change in an asynchronous serial data signal, and serial data after the oscillation is restarted is adopted as control data. In a data communication method for a battery-powered small device, which comprises an apparatus and a data transmitter for transmitting asynchronous serial data to the data receiver, the data receiver restarts oscillation of a reception clock, and then controls data. In the data communication method for a small battery-powered device, the data transmitter transmits dummy data unrelated to the control data until the start of reception.