JP3063376B2 - PWM signal communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PWM signal communication apparatus for performing communication by performing PWM modulation on transmission data.

[0002]

2. Description of the Related Art Conventionally, in a PWM signal communication apparatus of this type, as disclosed in, for example, Japanese Patent Application Laid-Open No. 3-151735, a transmitting apparatus first transmits a reference pulse having a preset pulse width. The data pulse is transmitted first, and thereafter, a data pulse in which arbitrary data is PWM-modulated according to the data value is transmitted. Then, the receiving device first receives the first reference pulse and measures the pulse width,
After recognizing the type of the arbitrary data transmitted thereafter, the subsequent data pulse is received and taken in.

[0003]

However, in such a conventional PWM signal communication device, the amount of data transmitted from the transmission device is small and there is relatively no problem when the transmission speed is low, but the amount of data transmitted is large. If the transmission speed is high, the receiving device may not be able to process received data normally.

[0004] Generally, a signal output circuit of a transmitting device and a signal input circuit of a receiving device include a transistor, a resistor,
Although it is composed of electronic components such as comparators, each of the inherent characteristics of these components originally has a difference, and the characteristics change depending on the temperature environment and the power supply voltage and current used. is there. For example, as shown in FIG. 4, the transmission pulse train Pout formed by the transmission control unit in the transmission device is not directly taken into the reception control unit in the reception device, but the reception pulse train P that is actually taken in.
This is because “in” includes a pulse rising delay “a” and a pulse falling delay “b”.

In particular, in a vehicle electronic control device or the like that controls an engine or the like using a plurality of CPUs, it is necessary to process a large amount of data at high speed in order to improve control accuracy. Although it is required to increase the data transmission speed between the conventional PWMs as described above,
In the signal communication device, as the data transmission speed increases, the difference between the transmission pulse train of the transmission CPU and the reception pulse train of the reception CPU cannot be ignored. Further, in the electronic control unit for a vehicle, the operating temperature environment of the transmitting device and the receiving device may be completely different depending on the mounting position, for example, in a vehicle compartment and an engine room, and they also change during use. . Therefore, it has been very difficult to design a vehicle electronic control device in consideration of these conditions in advance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and is not subject to the use temperature environment of each communication device and the characteristics of electronic components to be used. It is intended to provide a signal communication device.

[0007]

That is, according to the present invention, which has been made to achieve the above object, as shown in FIG. 1, a data pulse obtained by PWM-modulating transmission data in accordance with a data value thereof is set in advance. A transmission device including transmission control means for forming a transmission pulse train from a reference pulse having a pulse width, and signal output means for transmitting the transmission pulse train to a transmission line; and a signal for receiving the transmission pulse train from the transmission line. In a PWM signal communication device including an input unit and a reception control unit configured to process the received pulse train as reception data, a pulse width for detecting a pulse width of the reference pulse is provided to the reception unit. Detecting means for detecting a pulse width generated in a transmission / reception process from a pulse width of the reference pulse detected by the pulse width detecting means and a predetermined pulse width of the reference pulse; Deviation detecting means for detecting the difference, and correcting means for correcting the pulse width of the received PWM modulated data pulse based on the deviation and inputting the corrected data pulse as received data to the reception control means. The gist is a PWM signal communication device characterized by the above.

[0008]

In the PWM signal communication apparatus of the present invention configured as described above, first, in the transmission apparatus, the transmission control means sets in advance the data pulse obtained by PWM-modulating the transmission data in accordance with the data value. A transmission pulse train is formed from a reference pulse having a pulse width. Then, the signal output means sends out the transmission pulse train to the transmission path.

In the receiving apparatus, the signal input means takes in the transmission pulse train as a reception pulse train. Then, first, the pulse width detecting means detects the pulse width of the reference pulse from the received pulse train. Next, the deviation detecting means obtains a deviation of the pulse width generated in the transmission / reception process from the detected pulse width of the reference pulse and the pulse width of the reference pulse set in advance with the transmitting device. And the correction means,
Each pulse width of the subsequently received data pulse is sequentially corrected based on the deviation obtained in the above procedure, and the corrected data pulse is input to the reception control means as reception data.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of a vehicle engine fuel injection control system according to an embodiment to which the present invention is applied.

As shown in FIG. 2, the vehicle engine fuel injection control system of this embodiment calculates control data such as a target fuel injection amount and injection pressure from operating parameters such as a throttle and an engine speed. A transmission-side electronic control unit (hereinafter simply referred to as an ECU) 1 that transmits the control data as transmission data, and receives the transmitted control data and drives an actuator that controls a fuel injection amount, an injection pressure, and the like based on the received control data. The receiving ECU 2 and the transmitting ECU 1
And a communication line 3 that connects the reception side ECU 2.

The transmitting ECU 1 calculates the control data, modulates the control data by PWM, and sets the PWM
The transmission-side microcomputer (hereinafter simply referred to as CPU) 4 for forming a transmission pulse train from the modulated data pulse and a reference pulse having a preset pulse width, a transistor, a resistor, and the like. It comprises an output circuit 5 for transmitting a transmission pulse train to the communication line 3 and an input circuit (not shown) for inputting signals from various sensors.

The receiving ECU 2 includes a comparator,
An input circuit 6 configured by a resistor or the like, for receiving the transmission pulse train from the communication line 3, correcting a pulse width of a data pulse received by the input circuit 6, and processing the corrected data pulse as received data. It comprises a CPU 7 and a load drive circuit (not shown) for driving various actuators.

That is, in the vehicle engine fuel injection control system of the present embodiment, the communication line 3 serves as a transmission path, and the transmitting ECU 1 functions as a transmitting device and the receiving ECU 2 functions as a receiving device. Among them, the transmission-side CPU 4 functions as transmission control means, and the output circuit 5 functions as signal output means.
Further, the input circuit 6 serves as a signal input means,
Reference numeral 7 functions as reception control means having a pulse width correction function of the reception data pulse.

Next, communication signals used for data communication between the ECUs 1 and 2 will be described with reference to FIG. In FIG. 4, Pout represents a transmission pulse train formed by the transmission-side CPU 4, and Pin represents a reception pulse train taken into the reception-side CPU 7.

As shown in FIG. 4, the transmission pulse train Pout
Starts with a transmission reference pulse P1 having a predetermined pulse width T1 (500 μs in this embodiment), and thereafter sets control data calculated by the transmission-side CPU 4 to P
Three types of WM-modulated transmission data pulses PQ1, PP1,
PT1 is a continuous configuration, and is formed at a predetermined cycle T (set to 10 ms in the present embodiment) by the transmitting CPU 4. In the three types of transmission data pulses, the pulse width TQ1 of the transmission data pulse PQ1 indicates the fuel injection amount, the pulse width TP1 of the transmission data pulse PP1 indicates the fuel injection pressure, and the pulse width TT1 of the transmission data pulse PT1 indicates the fuel injection timing. Are respectively shown.

Next, the transmission pulse train Pout passes through the output circuit 5, the communication line 3, and the input circuit 6, and is transmitted to the reception pulse train Pout.
It is taken into the receiving side CPU 7 as in. However, due to this transmission / reception process, the received pulse train Pin includes a pulse rising delay a and a pulse falling delay b uniformly with respect to the transmission pulse train Pout, as shown in FIG.

Therefore, the respective pulse widths T2, TQ2, TP2, TT2 of the reception reference pulse P2 and the reception data pulses PQ2, PP2, PT2 are different from the pulse width of each transmission pulse by (ba). In the embodiment, the maximum change is set to (b−a) = ± 100 μs). For example, the pulse width T2 of the reception reference pulse P2 is set.
Takes a value from 400 μs to 600 μs.

The transmission data pulses PQ1, PP1, P
Each pulse width TQ1, TP1, and TT1 of T1 is
The value is set to at least 750 μs or more so that the PU 7 can accurately distinguish between the reception reference pulse P2 and the reception data pulses PQ2, PP2, and PT2.
That is, the minimum value of the pulse width of the reception data pulse is equal to the maximum value (600 μm) of the pulse width T2 of the reception reference pulse P2.
Since this is sufficiently larger than s), the identification can be performed accurately.

Next, the pulse width correction processing of the received data pulse, which is executed under the control of the receiving CPU 7, will be described with reference to the flowchart shown in FIG. In the vehicle engine fuel injection control system of the present embodiment, the reception pulse train Pin received by the input circuit 6 is transmitted to the reception side CPU.
The correction processing shown in FIG. 3 is started each time the reception pulse rises and falls.

First, when a reception pulse is input to the reception-side CPU 7, the edge of the reception pulse is determined in S110. When it is determined that the edge is a rising edge, the process proceeds to S120, and in S120, an internal timer of the CPU 7 is started to measure the pulse width of the reception pulse. Then, one round of processing is completed.

Next, when it is determined in S110 that the edge of the received pulse is falling, the flow shifts to S130. In S130, the time from the rise to the fall of the received pulse, that is, the pulse width of one pulse is measured from the timer value of the internal timer of the CPU 7 at that time. Then, in S140, the pulse width of the received pulse is 600
If it is less than μs, the received pulse is the reception reference pulse P2
And the process moves to S150.

Here, the processes from S110 to S140 function as pulse width detecting means of the reference pulse. In step S150 which executes the process as the deviation detecting means, the pulse width T1 of the transmission reference pulse P1 set in advance between the transmission side CPU 4 and the pulse width T2 of the reception reference pulse P2 measured in S130 is subtracted. Calculate H. Then, in S160, the counter C for judging the next received data is cleared, and one round of processing is completed.

On the other hand, if it is determined in S140 that the received pulse is not the reception reference pulse P2, the flow shifts to S170. In S170, it is determined whether the value of the counter C cleared in S160 is 0, and if C = 0,
It recognizes that the pulse received this time is the next received data pulse PQ2 after the reception reference pulse P2, and shifts to S180. In S180, the corrected fuel injection amount data TQ is obtained by subtracting the deviation H calculated in S150 from the pulse width TQ2 of the reception data pulse PQ2 measured in S130. Then, in S190, the counter C for judging the next received data is incremented, and the cycle of processing is completed.

Next, at step S170, the value of the counter C becomes 0.
When it is determined that it is not, the process proceeds to S200. S200
Then, it is determined whether or not the value of the counter C is 1, and C =
If 1, the received pulse is the received data pulse P
It recognizes that it is the next received data pulse PP2 after Q2, and shifts to S210. In S210, the corrected fuel injection pressure data TP is obtained by subtracting the deviation H calculated in S150 from the pulse width TP2 of the received data pulse PP2 measured in S130. Then, in S190, the counter C for judging the next received data is incremented, and the cycle of processing is completed.

At S200, the value of the counter C becomes 1
If it is determined that it is not, the process proceeds to S220. S220
Then, it is determined whether or not the value of the counter C is 2, and C =
If 2, the received pulse is the received data pulse P
It recognizes that it is the reception data pulse PT2 to come after P2, and shifts to S230. In S230, the fuel injection timing data TT after correction is obtained by subtracting the deviation H calculated in S150 from the pulse width TT2 of the reception data pulse PT2 measured in S130. Then, in S190, the counter C for judging the next received data is incremented, and the cycle of processing is completed. As described above, S180,
S210 and S230 function as correction means.

Here, when it is determined in S220 that the value of the counter C is not 2, the flow shifts to S240, and the occurrence of a communication error is detected. As described above, since the counter C is cleared in S160 only when the reception reference pulse P2 is received, C = 0 is not set until the next reception reference pulse P2 is received. That is, when an extra pulse is received during the predetermined period T, the counter C is set in S190.
Is 3 or more, a communication error is detected in S240, and in this case, the process is repeated from the pulse width measurement process in S110. In other words, S220 and S240 are processes for detecting a communication error when a pulse other than a data pulse such as noise is erroneously received.

After the above-described processing, the receiving CPU 7 performs processing for driving the actuator based on the corrected received data TQ, TP, TT. As described above, in the vehicular engine fuel injection control system according to the present embodiment, the reception-side CPU 7 determines the pulse width T2 of the received reception reference pulse P2 and the transmission reference pulse P1 set in advance with the transmission-side CPU 4. The pulse width of the transmission data pulse formed by the transmission-side CPU 4 is corrected by sequentially calculating the difference between the pulse width T1 and the pulse width T1. The width and the pulse width of the reception data pulse as data processed by the reception side CPU 7 are exactly the same. In addition, by counting the number of data pulses between the reception reference pulse P2 and the next reception reference pulse P2, it is possible to detect the entry of noise or the like. Therefore, the transmitting ECU 1 and the receiving ECU
2, the receiving ECU 2 can drive the actuator faithfully based on the control data calculated by the transmitting ECU 1 without being influenced by the use temperature environment and voltage change, the characteristics of the electronic components used, and the like. Resistance can also be improved.

In the vehicle fuel injection control system of this embodiment, the pulse width of the received data pulse is corrected by the pulse width of a fixed reference pulse arranged between a series of data pulse trains. It is also possible to correct the pulse width of the received data pulse by keeping the interval constant and using this as the pulse width of the reference pulse. In the present embodiment, three control data
It is about the case of communication between CPUs,
The present invention is naturally applicable regardless of the number of communication data and CPUs.

[0030]

As described above, in the PWM signal communication apparatus according to the present invention, the receiving apparatus uses the pulse width of the received data pulse based on the pulse width of the reference pulse set in advance with the transmitting apparatus. , So that the pulse width of the transmission data pulse formed by the transmission control means in the transmitting device and the receiving device are independent of the operating temperature environment of each communication device, the characteristics of the electronic components used, and the like. The pulse width of the received data pulse as the data to be processed by the reception control means is exactly the same.

Therefore, when designing each communication device, PWM signal communication can be executed at high speed and accurately without paying special attention to various characteristics of electronic components to be used, temperature environment, and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating the configuration of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a vehicle engine fuel injection control system according to the embodiment.

FIG. 3 is a flowchart illustrating a pulse width correction process of a received data pulse in the receiving apparatus according to the embodiment.

FIG. 4 is a time chart for explaining a pulse delay of a reception pulse train generated with respect to a transmission pulse train.

[Explanation of symbols]

 1, 2 ... electronic control unit (ECU) 3 ... communication line 4, 7 ... microcomputer (CPU) 5 ... output circuit 6 ... input circuit

Claims (1)

(57) [Claims] 1. A method for transmitting transmission data according to a data value
A transmission device comprising: transmission control means for forming a transmission pulse train from an M-modulated data pulse and a reference pulse having a preset pulse width; and signal output means for transmitting the transmission pulse train to a transmission path. A receiving device comprising: signal input means for receiving the transmission pulse train from the transmission path; and reception control means for processing the received pulse train as reception data. A PWM signal communication device comprising: Pulse width detection means for detecting the pulse width of the reference pulse; and detecting a deviation of the pulse width generated in the transmission / reception process from the pulse width of the reference pulse detected by the pulse width detection means and a predetermined pulse width of the reference pulse. Deviation detecting means for correcting the pulse width of the received PWM-modulated data pulse based on the deviation, and transmitting the corrected data pulse to the received data pulse; PWM signal communication apparatus characterized in that a, a correction means for inputting to said reception control means as.