JP6622848B2 - Apparatus and method for transmitting control information in data communication via serial interface - Google Patents

Description

Detailed Description of the Invention

  The present invention relates to an apparatus and method for transmitting control information in data communication via a serial interface.

  Various components in a processor-controlled system communicate with each other through an interface. At that time, it is necessary to satisfy certain rules in order to perform error-free data communication.

  In order to obtain a predetermined data rate, a constant reference frequency is usually generated by an oscillator in the transmitter and receiver. At this time, the reference frequency (that is, effective data rate) of the transmitter and the receiver may be slightly shifted from each other to generate a data transmission error. To prevent this problem, start and stop bits are used. This causes the receiver to re-synchronize each time a new character starts. If the line is idle, the receiver monitors the line until it detects the start bit front edge (eg, logic level changes from "1" to "0"). The detection time point can be used as a start trigger, and after detection, the line is queried or sampled at a predetermined time interval for each expected bit of consecutive characters. At this time, the receiver sets the time of the query so as to match the middle of the bits. As a result, for example, data bit 0 is queried at a time point 1.5 bits after the front edge of the start bit, and data bit 1 is queried at a time point 2.5 bits after the front edge of the start bit. When the stop bit is reached, the receiver starts “free execution” and waits until the next start bit.

  The stop bit needs to secure a predetermined logic level on the transmission line. Specifically, if the logic level of the last bit of the character is “0”, the receiver may not be able to distinguish this last bit from the start bit of the next character that may immediately follow. Therefore, the opposite level (eg, logic level “0”) must always come before each start bit (eg, logic level “1”). This is guaranteed by the stop bit. Since the lines are at the same level in the idle state, this method can be used even after a long transmission pause. The receiver operates substantially synchronously with the transmitter only as long as the character continues, and stops this synchronization at the end of each character. For this reason, this transmission method is called asynchronous operation.

  In addition, a delay time for processing the last character received by the receiving apparatus is given by the stop bit. For this purpose, stop bits having a length of 1.5 bits or 2 bits are used.

  In addition to the data bits, so-called parity bits may be transmitted. Error control can be easily performed by this parity bit. If even parity is used, if the transmitted character has an odd number of bits set to logic level “1”, the transmitter sets the parity bit to logic level “1”, for example. On the other hand, if the character has an even number of bits, the parity bit is set to logic level “0”. Here, the receiver checks whether the logical level of the received parity bit correctly reflects the parity of the received data bit based on the same rule. Thus, if an error occurs in any of the data bits during transmission, the error can be detected by the receiver.

  As an example of such an asynchronous serial interface, there is a universal asynchronous receiver transmitter (UART) interface which is an electronic circuit that implements a digital serial interface. As this interface, there is a functional block of a stand-alone electronic component (for example, a UART chip or an element) or a highly integrated component (for example, a microcontroller). The UART interface has a function of transmitting and receiving data via a data line, and is a standard for a serial interface in a personal computer (PC) and a microcontroller. In the industrial field, this interface is widely spread along with various interfaces (for example, RS-232 and EIA-485).

  In the UART interface, data is transmitted as a serial digital data stream. This serial digital data stream includes a fixed frame consisting of start bits, 5 bits up to 9 bits, optional parity bits for detecting transmission errors, and stop bits. The stop bit can be extended to 1.5 times or 2 times the standard transmission time of the bit so that the receiver can secure a synchronization time for the clock of the received data.

  Main examples of the UART interface include a microcontroller, a communication component in a computer, a stand-alone integrated circuit, and a chipset (in the form of a hardware description language for integration in a field programmable gate array (FPGA)). There is a so-called “software UART” that is provided only as a partial function and program sequence and directly drives a given input / output pin. Most of the data transmitted and received is transmitted to the UART in parallel via, for example, a bus external to the CPU.

In the case of controlled devices (hereinafter controlled devices ), in many cases control information (eg trigger pulses) is transmitted as fast as possible between the transmission of control information and the triggering or activation of the controlled device . It is necessary to minimize the delay. In this way, for example, the lighting device is controlled by the trigger of the camera device. In this case, conventionally, the required high-speed trigger pulse is transmitted via an additional line, which increases complexity and requires more space.

  Therefore, it is desirable to be able to realize transmission of fast trigger pulses and other control information without additional lines in order to reduce complexity and size as much as possible. This is desirable, for example, when data communication via only one line is performed between two microcontrollers (camera and lighting) using the standard UART protocol.

  Accordingly, an object of the present invention is to provide an interface capable of transferring control information through a serial data line with almost no delay.

  According to the present invention, the object is to provide a device according to claims 1, 2, a camera device according to claim 8, a lighting device according to claim 10, a method according to claims 11 and 12, and a claim. This is achieved by the computer program according to item 13.

As a result, reception of control information (eg, trigger pulse) and insertion or integration into a data stream is performed at a predetermined bit position immediately after the start bit of the character following reception of the control information and before the stop bit of the character. Done in At the receiver side, that is, the controlled device , the start bit of the character of the data stream is detected, and the control information is extracted from the data stream, which is the data stream immediately after the detected start bit. This is performed at a predetermined bit position of the character. In this way, the transmission of the control information is performed using at least one bit position of the character of the data stream, thereby determining the control information while keeping all the effects of standard serial interface communication. One or more commands can be executed substantially faster. Therefore, by connecting an additional input terminal to the data stream, the control information can be transmitted in advance of the period of the next character to be transmitted until the control information is supplied to the receiving side. The delay time (standby time) can be substantially shortened.

According to a first beneficial development, at the first bit position after the start bit of the character of the data stream, the control information is inserted, for example by an integration unit . As a result, the control information can be easily transmitted as fast as possible. Specifically, the detection of the control information on the receiving side is not performed after 10 bits (that is, after the transmission of the next character of the data stream is completed), but preceded by 2 bits (the start bit and the first of the character). Data bits) after. As a result, the transmission time of the control information is shortened from, for example, 87 microseconds to about 18 microseconds.

  According to a second useful development, the length of the control information is 1 bit. In this simplest embodiment, only one character bit of the data stream can be used to control one device at the other end of the data line.

According to a third beneficial development, the control information indicates a trigger command that activates the controlled device . This enables triggering with a short standby time. Thus, for example, an input terminal (input pin) can be added to a standard UART communication interface to facilitate trigger command processing.

According to a fourth beneficial development, the control information has a length of at least 2 bits and includes address information starting from the second bit for addressing the controlled device . By this means, a plurality of devices can be controlled via a serial interface having only one data line, and the currently controlled device is controlled by the address information transmitted in the data stream (for example, an address (Using a decoder).

  According to a fifth beneficial development, the camera device functions as a master device in the serial transmission of the control information. Accordingly, the camera device controls the illumination function at high speed using the serial interface.

  Examples of the components of the apparatus proposed to achieve the above object include discrete circuits, integrated circuits (for example, application-specific integrated circuits (ASIC)), programmable circuits (for example, field There is a programmable gate array (FPGA). These function individually or as a whole. In particular, the camera apparatus includes an FPGA as a central element having an improved interface function. Further, there is a software program or software routine that embodies the steps recited in the method claims, whereby the microprocessor processor is controlled to execute the steps.

Hereinafter, the present invention will be described in more detail based on preferred embodiments with reference to the drawings.
FIG. 1 is a schematic block diagram of a serial data transmission system for communication between a camera device and a lighting device according to the first embodiment.
FIG. 2 shows a schematic time chart based on the waveform of serial digital data transmission.
FIG. 3 shows a schematic block diagram of a transmission-side transmission unit according to the second embodiment.
FIG. 4 is a schematic block diagram of a receiver-side transmission unit according to the second embodiment.

  In the following embodiments, a high-speed and simple control of the illumination device by the camera device via the UART interface, which is executed by the microcontroller, will be described. In particular, the description shows the improvement of a serial standard communication interface (eg, UART) with a short (and thus fast) command detected via an additional input terminal (input pin). Since only one communication line can be used, the camera preferably operates as a master. In each embodiment, communication is performed via a UART interface, which is a widely used standard interface, and the protocol is already integrated into many microcontrollers, so it needs to be specifically programmed. Because there is no.

  FIG. 1 shows a schematic block diagram of a serial data transmission system for data communication using an integrated control mechanism according to the first embodiment. This system is a transmission system between a camera device 10 (such as a surveillance industrial camera) and a lighting device 20 (such as a controllable light source) comprised of light emitting diodes (LEDs) 27. FIG. 1 shows only the components that are considered necessary for the description of the functions of the first embodiment, and does not show the components for other supplementary functions for the sake of brevity.

  The camera device 10 includes a programmable circuit (FPGA) 14. This circuit 14 is programmed according to the desired function of the first embodiment. Thereby, the circuit 14 has the trigger generating means 13. The means 13 transmits a trigger word including the binary control command B to the UART interface function 15 as a trigger signal. This transmission is performed according to manual control, program control, or a sensor-controlled trip function. The function 15 is also executed by the circuit 14. The integrated UART interface function 15 is supplied with binary data D (output via this UART interface) from the microcontroller (μC) 11 (also integrated with the circuit 14) or received from the outside. D is transferred to the microcontroller 11.

  The operation of the UART interface function 15 in the first embodiment is performed such that the microcontroller 11 and the trigger generation means 13 selectively use the UART interface function 15 individually. In order to realize this, the microcontroller 11 cancels the UART interface function 15 on the basis of the permission signal F supplied (from the trigger generating means 13 or the like), for example, so that the function 15 can be used by the trigger generating means 13. To do.

  Thus, the control command B such as a trigger is not inserted into the existing data of the microcontroller 11. However, the trigger generating means 13 supplies the trigger word to autonomously transmit the trigger word including the control command B to the UART interface function 15. The trigger word includes bits corresponding to the activation of the trigger (for example, the start bit and the first bit of the control command B). Other bits remain unused or contain supplemental information (eg, “light on”, “send error status”, etc.) determined at an early stage, for example).

  When the permission signal F is supplied, the microcontroller 11 is controlled so that the UART interface function 15 is temporarily released and control information (for example, a trigger) is transmitted. The transmission system then enters a control mode, i.e. a mode in which no data communication is performed, and the control information can be transmitted directly at any time. Outside this mode, control information is always inserted into the next data byte, resulting in a waiting time.

  The trigger word including the control command B created by the trigger generation means 13 is inserted after the serial data stream of the binary data D after the UART interface function 15 is released. As a result, the serial output bit stream of the UART interface is composed of data words including the integrated control command B.

  The circuit 14 is connected to a multipurpose interface (for example, a general purpose input / output interface (GPIO)) which is a contact terminal of the camera device 10 via a UART interface function. The action of the multipurpose interface as an input or output interface can be arbitrarily programmed by the circuit 14.

  Data D including the integrated control command B output via the multipurpose interface is transferred to the lighting device 20 as a serial data stream through the data line 100. In the lighting device 20, the data D is supplied to a UART interface function 25 integrated with the microcontroller 21 and is subjected to appropriate processing (for example, adjustment of brightness and luminance of the LED 27). Prior to this, the integrated control command B is separated from the data stream by an appropriate extraction or branch function and supplied to the input / output interface 22 of the microcontroller 21. It is also possible to control the extraction or branch function by the permission signal F or a signal derived from the permission signal F so that a control command is supplied to the input / output interface 22. Then, according to the control program of the microcontroller 21, the received control command B activates a desired function of the lighting device 20 (for example, switching the LED 27 on and off).

  Next, a specific example of waveforms generated by the serial interface and a method for integrating the control commands B will be described in detail with reference to FIG.

  FIG. 2 shows a schematic time chart based on the waveform of serial digital data transmission. Asynchronous serial data streams (eg, data streams created by the UART interface function 15 of FIG. 1) have binary levels (eg, logic levels “0” and “1”). The upper diagram of FIG. 2 represents a binary data stream, and the lower diagram represents an inverted voltage level (± 15 V) corresponding to the binary data stream in an interface based on the RS-232 standard.

  A feature of the serial interface is that a dedicated clock signal is not required on the transmission line in the asynchronous operation mode described above. Instead, the receiver is synchronized by the start and stop bit switching edges of the data stream characters and the set baud rate (in this case, corresponding to the bit rate). The transmission using the start bit can be started at any time, and this serial interface is called asynchronous. To ensure synchronization, the number of bits that can be transferred is limited. Long data streams can lose synchronization, which can result in misinterpretation of the data stream and mistransmission.

  As with the UART protocol, the shortest message (a data word or character consisting of 8 data bits including the start bit, stop bit, and most significant bit (MSB7) and least significant bit (LSB0)) is shown in FIG. Ignoring the parity bits shown in Fig. 1, it has a length of 10 bits and transmission takes about 87 microseconds with a maximum possible data rate of 115 kilobaud. The delay time (waiting time) until the next character transmission may be too long depending on the application.

By integrating an additional input terminal (input pin) into the data stream in the UART interface function 15 of FIG. 1, two bits (start bit and first data bit) are preceded by a control command B (eg, trigger signal). ) Detected later by the receiver (lighting device 20 in FIG. 1). As a result, the transmission time of the control command B is reduced to about 18 microseconds.

  If necessary, additional commands can be sent by evaluating with additional bits (eg, subsequent second data bits, third data bits, etc.). However, the waiting time increases by about 9 microseconds for each additional bit.

Furthermore, it is possible to indicate the controlled device by indicating that the first data bit indicates the control command B and the subsequent two bits indicate an address. This makes it possible to control (for example, triggering) four devices (addresses “00”, “01”, “10”, and “11”) with a waiting time of 4 bits (36 microseconds). Become.

  FIG. 3 is a schematic block diagram of a transmitter-side command transmission unit according to the second embodiment. The control command B is inserted directly at the reserved bit position in the data word. The insertion can be performed by correspondingly adapting the bit width of the data word. The UART interface function 15 can be used simultaneously by the trigger generating means 13 and the microcontroller 11, and it is not necessary to release the UART interface function 15.

  A data stream sent from the microcontroller 11 including a start bit ST, a stop bit SP, and a continuous character including 8 bit positions is supplied to an encoder (COD) 122. The encoder 122 is integrated into the UART interface function 15 shown in FIG. Encoder 122 includes an additional input terminal for control command B having an active binary value (eg, logic level “1”) upon detection. The control command B is inserted into the data stream at a predetermined data bit position (here, bit position 2 or the first data bit) after the start bit of the immediately following character. The predetermined bit position is set by optional programming information P, for example. In the output of the encoder 122, the character pattern 200 shown in FIG. 3 is acquired immediately after the detection of the active control command B. This command B is supplied to the data line 100 to control the lighting device.

  FIG. 4 shows a schematic block diagram of a receiver-side command transmission unit according to the second embodiment.

  On the receiver side, for example, a character pattern 200 including an integrated control command created by the encoder 122 of FIG. 3 and transmitted through the data line 100 includes a detector (DET) 222 and a demultiplexer configured as a controlled changeover switch. Or it is supplied to the extractor 221 in parallel. Extractor 221 has a data output for data D and a control output for control command B, which are selectively connected to the input data stream using a changeover switch in response to a control signal supplied from detector 222. Can be made. As soon as the detector 222 detects the start bit ST of the character in the received data stream, it controls the extractor 221 in a time correction manner. Thereby, the detector 222 (based on the configuration of the control command B) determines the predetermined value of the control command B (here, bit position 2 or the first data bit of 1 bit length) during a period of one or several data bits. The data stream is connected to the control output at a bit position (which can be arbitrarily set by the programming information P here). As a result, the control command B is extracted (if available) and supplied to the control output unit for further processing (eg, triggering of the lighting device).

The present invention is not limited to the above-described embodiment. Various modifications may be made within the scope of the following claims. In particular, the present invention is not limited to data communication including integrated control between a camera device and a lighting device, and is not limited to a UART interface. Other serial interfaces can of course be used as well. The present invention can be used in connection with all serial data transmission between a device suitable for control and a controlled device . Furthermore, the number and position of control bits in the character of the serial data stream is not limited at all.

  In summary, an apparatus and method for transmitting control information in a serial data stream at high speed using a serial interface is described. The control information is inserted into the data stream at a predetermined bit position immediately after the start bit of the character after reception of the control information and before the stop bit of the character in the data stream. On the receiver side, the start bit of the character is detected, and control information is extracted from the data stream at a predetermined bit position of the character immediately after the detected start bit.

FIG. 1 is a schematic block diagram of a serial data transmission system for communication between a camera device and a lighting device according to the first embodiment. FIG. 2 shows a schematic time chart based on the waveform of serial digital data transmission. FIG. 3 shows a schematic block diagram of a transmission-side transmission unit according to the second embodiment. FIG. 4 is a schematic block diagram of a receiver-side transmission unit according to the second embodiment.

Claims (19)

An apparatus for transmitting control information in a serial data stream using the serial interface,
A receiving terminal for receiving control information for the controlled device ;
An integrated unit for receiving a data stream for the controlled device;
The data stream for the controlled device has a start bit and a stop bit for synchronization, and a new synchronization occurs based on the start bit at the start of each new character and reaches the stop bit Then, free execution is resumed and the next start bit is awaited, and the integration unit receives a predetermined value immediately after the start bit of the character after receiving the control information and before the stop bit of the character of the data stream. in bit position, inserting the control information to the data stream,
apparatus. A device for receiving control information in a serial data stream using a serial interface,
A detector unit for detecting a start bit of the character of the serial data stream for the controlled device, the serial data stream for the controlled device having a start bit and a stop bit for synchronization, A new synchronization occurs based on the start bit at the start of a new character, and when the stop bit is reached, free execution resumes and the next start bit waits ,
The apparatus further includes:
In response to detecting the start bit at a predetermined bit position of the character of a bit position wherein Shiriarude over data stream immediately following the detected start bit, from the serial data stream for the controlled device An extraction unit for extracting the control information for the controlled device ;
Comprising a device. The integration unit is configured to insert an entire character including the control information into the data stream after releasing a further input terminal for receiving data of the data stream from a data source. Equipment. The apparatus of claim 1, wherein the integration unit is configured to insert the control information at a first bit position after the start bit of the character of the data stream.   The apparatus according to claim 1 or 2, wherein the control information has a length of 1 bit.   6. The apparatus of claim 5, wherein the control information indicates a trigger command that activates a controlled device. The control information has a length of at least 2 bits;
The apparatus according to claim 1 or 2, wherein the control information includes address information starting from a second bit for addressing a device to be controlled.   The apparatus according to claim 1, wherein the serial interface is a universal asynchronous transceiver (UART) interface. A camera apparatus comprising the apparatus according to claim 1,
A camera device for controlling illumination using the control information.   The camera device according to claim 9, wherein the camera device functions as a master device in serial transmission of the control information. A lighting device comprising the device according to claim 2,
An illumination device that controls illumination of the illumination device using the control information. A method for transmitting control information in a serial data stream using the serial interface,
Inserting start and stop bits for synchronization on the receiving side into the data stream of the controlled device;
Receiving the control information for the controlled device and a data stream for the controlled device at an integrated unit ;
The integration unit inserts the control information into the data stream at a predetermined bit position immediately after the start bit of the character after receiving the control information and before the stop bit of the character of the data stream. And
Only including, a new synchronization based on the start bit at the start of each new character occurs, the reaches the stop bit free running resumes the start bit of the next is waiting method. A method for receiving control information in a serial data stream using a serial interface,
Detecting a start bit of the character of the serial data stream for the controlled device, wherein the serial data stream for the controlled device has a start bit and a stop bit for synchronization, A new synchronization occurs based on the start bit at the start of a new character, and when the stop bit is reached, free execution resumes and the next start bit waits,
The method further comprises:
In response to detecting the start bit, the serial data stream for the controlled device at a bit position immediately after the detected start bit and at a predetermined bit position of the character of the serial data stream from extracting the control information for the controlled device,
Including a method.   The method according to claim 12, wherein after the further input terminal for receiving data of the data stream from a data source is released, the entire character including the control information is inserted into the data stream.   14. A computer program that, when executed by processing means of a computer device, causes the computer device to execute the method according to claim 12 or 13.   A device for transmitting control information in a serial data stream using a serial interface,
  A receiving terminal for receiving control information for the controlled device;
  An integrated unit for receiving a data stream for the controlled device;
And the integration unit transmits the control information to the data stream at a predetermined bit position immediately after the start bit of the character after reception of the control information and before a stop bit of the character of the data stream. The control information has a length of 1 bit.   A device for receiving control information in a serial data stream using a serial interface,
  A detector unit for detecting a start bit of the character of the serial data stream;
  In response to detecting the start bit, the control information is extracted from the serial data stream at a bit position immediately after the detected start bit and at a predetermined bit position of the character of the serial data stream. An extraction unit;
The control information has a length of 1 bit. A method for transmitting control information in a serial data stream using a serial interface,
And receiving said control information for the controlled device, and a data stream for the controlled device in an integrated unit,
The integration unit inserts the control information into the data stream at a predetermined bit position immediately after the start bit of the character after receiving the control information and before the stop bit of the character of the data stream. And
The control information has a length of 1 bit.


  A method for receiving control information in a serial data stream using a serial interface,
  Detecting a start bit of the character of the serial data stream;
  In response to detecting the start bit, the control information is extracted from the serial data stream at a bit position immediately after the detected start bit and at a predetermined bit position of the character of the serial data stream. And
Including methods.