JP2003078514A - Data communication method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce any adverse influence such as a noise against the reception of radio or television broadcasting or the like with a simple configuration. SOLUTION: An IC 31 including a microcomputer in electronic control equipment 21 is provided with a clock generating circuit 33 for generating a clock signal of a random cycle. A data transmitting circuit 34 transmits data to the IC 32 synchronously with the clock signal. In the IC 32, the reception of data is performed by a data receiving circuit 37 synchronously with the clock signal to be received by a clock receiving circuit 36. The cycle of the clock signal is made random, and not fixed to any specific frequency so that it is possible to reduce the adverse influence of a high frequency or the like on the reception of radio or television broadcasting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication method and device for transmitting data in synchronization with a clock signal.

[0002]

2. Description of the Related Art Conventionally, a clock signal has been used as a timing reference when processing digital data in various electronic circuits. For example, in a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., data generated by a program operation based on a clock signal of the CPU via a data bus or an address bus. Processing and control are performed. A signal line forming an electronic circuit or a bus causes a delay in signal transmission and causes a dull signal waveform. It is necessary to define the timing in order to reliably transmit the data.

As the scale of electronic circuits increases, microcomputers and the like are integrated into ICs (semiconductor integrated circuits), and data communication is performed even among a plurality of ICs. In addition, even in a system in which a plurality of electronic control devices configured by electronic circuits are used and operate in cooperation with each other, data communication is performed between the electronic control devices. Basic methods of data communication include parallel communication for simultaneously transmitting a plurality of bits forming data and serial communication for sequentially transmitting one bit at a time. The serial communication may use an asynchronous start-stop method and a synchronous method in which a clock signal is included in a data signal for transmission. In the start-stop method, a start bit and a stop bit are added before and after a character that is a unit of data, and synchronization is performed for each character. In the synchronous system, in order to transmit data in synchronization with a clock having a fixed cycle, specific data is inserted for synchronization probability, and bit synchronization, character synchronization, or frame synchronization is performed. Further, in order to ensure data communication, there is also an asynchronous system in which a handshake is performed between the data transmitting side and the data receiving side. Various data communication methods are used as needed. The method of transmitting the clock signal and the data signal separately is capable of reliably transmitting the data by a simple process and is widely used.

FIG. 6 shows a configuration in which a clock signal and a data signal are separated and data communication is performed in an electronic control device 1 mounted on a vehicle such as an automobile. An electronic control device 1 called an ECU (electronic control unit) or the like is mounted on the vehicle to perform various controls related to traveling.
Also, for receiving radio and TV (television),
The electronic control device 2 is mounted. The electronic control devices 1 and 2
The power supply system 3 such as a battery operates as a common power source. The electronic control device 1 includes a power supply circuit 10 and ICs 11 and 12 such as a plurality of microcomputers.
The power supply circuit 10 stabilizes the power supply voltage supplied from the power supply system 3 to a predetermined voltage and supplies it to the ICs 11 and 12. Data communication is performed between the ICs 11 and 12, and data is transmitted in synchronization with the clock signal. The clock signal has a fixed cycle, and the data is determined based on the specific timing, for example, the transition time point of the logic level. The clock signal and the data signal are transmitted by a wiring pattern on the electronic circuit board in the electronic control device 1 or a signal wiring between the boards.

FIG. 7 shows a configuration in which a data signal is transmitted between a plurality of electronic control devices 1a and 1b mounted on a vehicle such as an automobile in synchronization with a clock signal having a constant cycle. Electronic control devices 1a, 1b such as ECUs mounted on automobiles
Perform, for example, control of the engine, control of the speed change mechanism, control of the braking mechanism, control of the airbag, etc., but mutual cooperation is also required and data communication is performed. The clock signal and the data signal are transmitted to the electronic control device 1a,
It is transmitted by a cable in a wire harness that interconnects 1b. In a vehicle, signal cables and power cords connected to the electronic control devices 1a and 1b and the electronic control device 2 are bundled as a wire harness.

Electronic control devices 1, 1a shown in FIG. 6 and FIG.
In the data communication by the clock synchronization between the ICs 11 and 12 in the electronic control device 1 and between the electronic control devices 1a and 1b as the processing speed of the electronic control device 1b is increased, the harmonic component of the clock frequency is a radio or TV. By propagating a harness including a signal cable and a power cord to another electronic control device 2 or by radiating in the harness,
It has a bad influence as noise. When the data signal is transmitted by serial communication, the clock frequency becomes higher, so that adverse effects such as noise are likely to occur.

As a prior art relating to the problem that a clock signal becomes noise to a radio receiver, Japanese Patent Laid-Open No. 2000-2000 is known.
-289545 gazette can be mentioned. In this prior art, in a vehicle equipped with a radio receiver, an electronic control unit that controls in synchronization with a clock signal changes the frequency of the clock signal according to the frequency of the radio wave being received by the radio receiver. As for the frequency of the clock signal, multiple frequencies can be switched, and if a frequency whose harmonics are different from the frequency of the received radio wave is selected, it can be said that it will not become noise to the received signal of the radio. .

[0008]

SUMMARY OF THE INVENTION In vehicle control, etc.,
As shown in FIGS. 6 and 7, data communication involving a clock signal is performed between a plurality of ICs 11 and 12 even within one electronic control device 1, and data involving a clock signal is also performed between a plurality of electronic control devices 1a and 1b. Communication takes place. JP 2000-
Even if the method of switching the frequencies of a plurality of clock signals is effective as in the prior art as disclosed in Japanese Patent No. 289545, the information about the frequency of the radio wave being received is received by a radio or TV receiver. It must be transmitted from the electronic control device 2 to the other electronic control devices 1, 1a, 1b. In this case, each electronic control device 1, 1a, 1b has
It must have a configuration for switching to an appropriate clock frequency according to the reception frequency. Furthermore, IC11,
12 must also have a function of inputting information on the reception frequency and switching the clock signal. However, in the ICs 11 and 12 and the electronic control devices 1, 1a and 1b,
Providing the function of selecting the clock frequency that does not cause interference by inputting the reception frequency information from the outside causes a large increase in cost.

An object of the present invention is to provide a data communication method and device which can reduce the adverse effect of noise on reception of radio or television broadcasting with a simple structure.

[0010]

DISCLOSURE OF THE INVENTION The present invention provides a data communication method for transmitting data in synchronization with a clock signal,
A data communication method characterized in that the cycle of a clock signal is randomly changed.

According to the present invention, the cycle of the clock signal for synchronously transmitting the data is changed at random, so that the cycle of the clock signal does not remain at a specific frequency, and radio or television due to harmonics or the like occurs. Can be reduced. When determining the period of the clock signal, information about the reception frequency of the radio or television is unnecessary, so there is no need for a configuration for transmitting that information, and it is possible to reduce adverse effects on reception with a simple configuration. You can

Further, according to the present invention, the transmission of the clock signal and the data is performed in the same electronic control device.

According to the present invention, in the same electronic control device, the clock signal propagates through the wiring pattern of the electronic circuit board or the signal cable between the electronic circuit boards to connect the electronic control device and the outside. It is possible to prevent the adverse effect as noise from being superimposed on the signal cable or the power cord and causing a propagation or radiation between the signal cable or the power cord as reception noise of the radio or television by changing the frequency at random.

In the present invention, the transmission of the clock signal and the data is performed between different electronic control devices.

According to the present invention, the frequency is randomly changed so that the clock signal may be adversely affected as noise by the propagation or radiation between the signal cables and the power cord between the electronic control devices as a noise in the reception of the radio or television. You can prevent it.

Further, the present invention is characterized by including clock generating means for generating a clock signal in a random cycle, and data transmitting means for transmitting data in synchronization with the clock signal generated by the clock generating means. Is a data communication device.

According to the present invention, when the clock generating means generates the clock signal in a random cycle, the data transmitting means transmits the data in synchronization with the clock signal. When receiving a clock signal and data, even if the cycle is random, the data can be fixed and received based on the specific timing of the waveform of the clock signal, so ensure the data transmission. You can Since the cycle of the clock signal changes at random, even if a radio wave of a specific frequency is received, it is possible to reduce adverse effects such as harmonic noise mixing.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of a data communication method which is an embodiment of the present invention. This embodiment is shown in FIG.
Similarly to the above, the electronic control device 21 mounted on the vehicle adversely affects the electronic control device 22 that receives radio or television broadcast as noise or the like by leaking out the clock signal used internally for data communication to the outside. Can be reduced. The electronic control device 21 and the electronic control device 22 are
Since the power supply system 23 such as a battery is commonly used and the signal cable and the like are bundled together with the power cord as a wire harness because they are mounted on the vehicle, the clock signal is easily propagated.

A power circuit 30 is provided in the electronic control unit 21.
And ICs 31 and 32 such as a plurality of microcomputers. The power supply circuit 30 stabilizes the power supply voltage supplied from the power supply system 23 to a predetermined voltage,
Supply to 32. In the present embodiment, the IC 31, which is the data transmission side, includes a clock generation circuit 33 that emits a clock signal in a random cycle, and a data that transmits data in synchronization with the clock signal generated from the clock generation circuit 33. A transmission circuit 34 and a data processing circuit 35 that sets data to be transmitted to the data transmission circuit 34 are included.
The IC 32 on the data receiving side includes a clock receiving circuit 36 for receiving a clock signal and a clock receiving circuit 36.
A data receiving circuit 37 for receiving a data signal in synchronization with a clock signal received by
And a data processing circuit 38 for processing the data received by. Data communication is performed between the ICs 31 and 32, and data is transmitted in synchronization with the clock signal. The clock signal has a random cycle, and the data is determined based on a specific timing in each cycle, for example, the transition time point of the logic level. The clock signal and the data signal are transmitted by the wiring pattern on the electronic circuit board in the electronic control device 31 or the signal wiring between the boards.

The clock generation circuit 33 randomly changes from the frequency Fclk of the basic clock signal at frequencies Fclk-δF to Fclk + δF which are within a certain range, for example, according to a preset random number table or an arithmetic expression for random number generation. Generates a clock signal. The frequency range is a frequency Fclk ÷ δK to Fclk × δK within a range that changes from the basic clock signal Fclk at a constant ratio δK.
Can also be It is also possible to switch a plurality of frequencies randomly. Further, the clock signal can be generated based on thermal noise or the like. Although the IC 31 is used as the transmitting side and the IC 32 is used as the receiving side, it is possible to include both the configurations of the transmitting side and the receiving side in the same IC to enable transmission and reception. Further, the present embodiment can also be used for data communication within the electronic control device 22 that receives radio or television broadcasts.

FIG. 2 shows an outline of a data communication method which is another embodiment of the present invention. In the present embodiment, portions corresponding to those of the embodiment of FIG. 1 are designated by the same reference numerals, and redundant description will be omitted. In this embodiment, as in FIG. 7, a plurality of electronic control devices 21 mounted on a vehicle such as an automobile.
A configuration for transmitting a data signal in synchronization with a clock signal between a and 21b is shown. However, the clock signal of the present embodiment has a cycle that changes randomly as in the embodiment of FIG. The clock signal and the data signal are sent to the electronic control device 21.
It is transmitted by a cable in a wire harness that interconnects a and 21b. In the vehicle, electronic control devices 21a, 21
The signal cables and power cords connected to b and the electronic control device 22 are bundled as a wire harness.

Electronic control device 2 on the transmission side of data communication
A clock generation circuit 33 and a data transmission circuit 34 are included on the 1a side. A clock receiving circuit 36 and a data receiving circuit 37 are included on the side of the electronic control device 21b that is the receiving side of the data communication. In order to enable bidirectional data communication, both the transmitting side and the receiving side of the data communication may be included.

FIG. 3 shows the concept of the conventional data communication shown in FIGS. 6 and 7 in comparison with the concept of the data communication according to the present invention shown in FIGS. 1 and 2. As shown in FIG. 3A, in the conventional data communication, data is set at a timing of rising from a low (L) level to a high (H) level in synchronization with a clock signal of a constant cycle, and a high (H) level is set. ) The level of the data signal is fixed on the basis of the time point at which the logic level transitions in the signal waveform, such as taking in data at the timing of falling from the level to the low (L) level. Since the cycle of the clock signal is constant, harmonic components having the same frequency are always generated from the clock signal, which may cause adverse effects such as noise mixing in the electronic control device 22 that receives a radio, a television, or the like. . In the embodiment of FIGS. 1 and 2, FIG.
As shown in (b), since the cycle of the clock signal changes at random, even if a specific frequency component adversely affects the frequency of radio or television broadcast received by the electronic control device 22, The frequency of frequency components is reduced, and the effect of noise can be reduced.

In FIG. 4, the data transmission circuit 34 of the IC 31 of FIG. 1 or the electronic control unit 21a of FIG. 2 synchronizes the data with the clock signal of the random cycle from the clock generation circuit 33 according to FIG. 3B. The procedure for transmitting the data is shown below.
The procedure is started from step a0, and the data for transmission is input in step a1. The data for transmission is given from the data processing circuit 35 or the like. At step a2, the rising of the clock signal is waited for. When the clock signal rises, in order to transmit data to another IC 32, data transmission is started to a signal line pattern for data communication or the like. In step a4, the process waits until the clock signal falls, and when the clock signal falls, the process returns to step a1. Thereafter, steps a1 to a4 are repeated, and data is transmitted in synchronization with a clock signal having a random cycle.

FIG. 5 shows a procedure in which the IC 32 of FIG. 1 or the data receiving circuit 37 of the electronic control device 21b of FIG. 2 receives the data together with the clock signal according to FIG. 3B. The procedure is started from step b0, and the transmitted data is input in step b1. In step b2, it is determined whether the level of the clock signal received by the clock receiving circuit 36 or the like has fallen from the high level to the low level. If there is no fall of the clock signal level, waiting until the fall occurs is repeated. If the clock signal falls at step b2, step b
The input data is confirmed in 1 and sent to the data processing circuit 38 or the like in step b3. In the next step b4, the rising of the clock signal is waited for, and the process returns to step b1.

The processing procedure shown in FIGS. 4 and 5 is basically the same as the procedure performed in the conventional data communication shown in FIG. 3 (a). However, in the present invention, the data communication method is characterized in that the cycle of the clock signal is randomly changed when transmitting data in synchronization with the clock signal. Since the cycle of the clock signal for synchronizing and transmitting data is changed at random, the cycle of the clock signal does not stay at a specific frequency, and it is possible to reduce the adverse effects on the reception of radio and television due to harmonics. it can. When determining the cycle of the clock signal, information about the reception frequency as in the prior art disclosed in Japanese Patent Laid-Open No. 2000-289545 is unnecessary, and therefore a configuration for transmitting the information is also unnecessary. It is possible to reduce the adverse effect on reception with a simple configuration. Further, the present invention is not only applied to an electronic control device mounted on a vehicle, but can be widely applied when it is necessary to perform data communication such as a stationary or portable information processing device or control device. it can.

[0027]

As described above, according to the present invention, the period of the clock signal for synchronizing and transmitting the data is randomly changed. Therefore, even if there is no information on the reception frequency of the radio or television, it is caused by noise. The adverse effect can be reduced. It is not necessary to input information about the reception frequency of the radio or television, and it is possible to reduce the adverse effect on reception with a simple configuration.

Further, according to the present invention, since the data communication in the same electronic control device is performed by randomly changing the cycle of the clock signal, the signal cable or the power supply for connecting the electronic signal to the outside by the clock signal. Even if it is superposed on a code and reaches an electronic control device or the like that receives radio or television by propagation or radiation between signal cables or power cords, it is possible to reduce the adverse effect as noise.

Further, according to the present invention, since the data communication between the electronic control devices is performed by randomly changing the cycle of the clock signal, the clock signal is propagated or radiated between the signal cables and the power cords, so that the radio or television. Even if it reaches an electronic control device or the like that receives, it is possible to reduce the adverse effect as noise.

Further, according to the present invention, the clock generating means generates the clock signal at a random cycle, and the data transmitting means transmits the data in synchronization with the clock signal. Even if the cycle is random, it is possible to reliably transmit data with a clock signal, and even when receiving radio waves of a specific frequency on a radio or television,
Since the clock signal has a random cycle, it is possible to reduce adverse effects such as mixing of harmonic noise.

[Brief description of drawings]

FIG. 1 is an electronic control device 2 according to an embodiment of the present invention.
It is a block diagram which shows schematically the electrical constitution for the data communication performed in 1.

FIG. 2 is a block diagram schematically showing an electrical configuration for data communication between electronic control devices 21a and 21b as another embodiment of the present invention.

FIG. 3 is a time chart showing the concept of data communication in the embodiments of FIGS. 1 and 2 in comparison with the concept of conventional data communication shown in FIGS. 6 and 7.

FIG. 4 is a flowchart showing an outline of a procedure for transmitting data in the embodiment of FIG. 1 or FIG.

5 is a flowchart showing an outline of a procedure for receiving data in the embodiment of FIG. 1 or FIG.

FIG. 6 is a block diagram showing a schematic electrical configuration of a state in which conventional data communication is performed in an electronic control device.

FIG. 7 is a block diagram showing a schematic electrical configuration of a state in which conventional data communication is performed between electronic control devices.

[Explanation of symbols]

21,21a, 21b, 22 Electronic control equipment 23 Power supply system 31,32 IC 33 clock generator 34 Data transmission circuit 35, 38 data processing circuit 36 clock receiver circuit 37 Data receiving circuit

Claims (4)

[Claims] 1. A data communication method for transmitting data in synchronization with a clock signal, wherein the cycle of the clock signal is randomly changed. 2. The data communication method according to claim 1, wherein the clock signal and the data are transmitted in the same electronic control device. 3. The data communication method according to claim 1, wherein the clock signal and the data are transmitted between different electronic control devices. 4. Data comprising: clock generating means for generating a clock signal at a random cycle; and data transmitting means for transmitting data in synchronization with the clock signal generated by the clock generating means. Communication device.