JPH0279539A - Serial communication system - Google Patents

Abstract

PURPOSE:To calculate the speed of revolutions of engine by generating an ignition signal as a variable period signal, transferring other serial data signal to a 2nd device synchronously with its generated timing and using a received timing as an interruption data. CONSTITUTION:The system is devised such that the serial data is sent by the delay of a prescribed time tau from the generation of an ignition signal to avoid noise at the ignition and when the succeeding ignition signal is not generated even a prescribed time T elapses from the transfer of the serial data synchronously with the ignition signal, the succeeding serial data is sent without awaiting the succeeding ignition signal. Thus, the serial data processing of the variable period signal at the sender side is not required, thereby quantity of the software is reduced.

Description

[Detailed Description of the Invention] [Summary] By synchronizing the transfer timing of serial data with the generation timing of another variable period signal, the period information of the variable period signal can be transmitted to the other device without converting it into serial data. do.

[Industrial application field]

The present invention relates to a serial communication system that transmits cycle information of a variable cycle signal based on the transfer timing of serial data.

[Prior Art] There are various types of controls for automobiles, and engine control and gear shift control are typical examples.

The engine control device controls the fuel injection amount, ignition timing, etc. by inputting engine rotation speed (N e ), vehicle speed, water temperature, throttle opening, etc. On the other hand, the transmission control device automatically controls the gear position based on the relationship between the engine speed and the vehicle speed, and many signals can be shared with the engine control device.

For this reason, conventionally, various signals are transferred from the engine control device 1 to the transmission control device 2 as shown in FIG. (a)
In this method, multiple signal lines are laid between device 1 and device 2,
Each signal is transferred through a dedicated signal line. Note that the Ne signal is created based on the ignition signal used in the device 1, and other signals include throttle opening, water temperature, etc.

On the other hand, in the method (b), the signal line between the devices 1 and 2 is unified, and various signals are converted into serial data and transferred.

[Problem to be solved by the invention]

The dedicated signal line system shown in FIG. 3(a) has the disadvantage that the number of signal lines installed between the devices 1 and 2 increases in proportion to the number of signals. In contrast, the serial communication method b) requires a single signal line regardless of the number of signals, but not only does it require processing to convert Ne (engine speed) into serial data on the equipment side, but it also requires conversion. If the number of bits of the transferred Ne data is large, it is necessary to divide the data into two or more transfers.

The present invention attempts to eliminate the drawback of the serial communication method shown in FIG. 3(b) by transmitting a variable periodic signal (for example, the ignition signal that is the basis of the Ne signal) as the transfer timing of serial data. be.

(Means for Solving the Problems) FIG. 1 is a diagram showing the principle of the present invention, in which 1 is a first device exemplified by an engine control device, and 2 is a second device exemplified by a speed change control device.

[Effect]

The first device 1 generates an ignition signal as a variable periodic signal, and transfers serial data of other signals to the second device 2 in synchronization with the generation timing.

The second device 2 uses the timing of receiving the serial data as interrupt data and counts the period of the ignition signal.

This allows the first device 1 to transmit the period of the ignition signal to the second device 2 without converting it into serial data.
Ne) can be calculated.

〔Example〕

FIG. 2 is a time chart showing an embodiment of the present invention, (a
) is a method in which serial data is sent after a fixed time τ delay from the generation of the ignition signal in order to avoid noise during ignition.

(b) is to send the next serial data without waiting for the next ignition signal if the next ignition signal is not generated even after a certain period of time T has passed after transmitting the serial data synchronized with the ignition signal. This prevents the data transfer efficiency from decreasing at low rotation speeds. In this case, a specific bit of the serial data can indicate whether or not it is synchronized with the ignition signal.

For example, if "'1°" as shown in the diagonal line indicates synchronization (for cycle counting), and "0°" as in the dashed line indicates something else, the device 2 will The ignition signal cycle can be detected from the data reception timing.

〔Effect of the invention〕

As described above, according to the present invention, even in the case of a serial communication system, there is no need for the sending device to convert a variable periodic signal into periodic serial data, and there is an advantage that the software I can be reduced accordingly.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram of the present invention, FIG. 2 is a time chart of an embodiment of the present invention, and FIG. 3 is an explanatory diagram of a conventional communication system. Applicant Fujitsu Ten Ltd. Representative Patent Attorney Minoru Aoyagi (a) Dedicated signal line method (b) Serial communication method Figure 3 is an explanatory diagram of the conventional communication method

Claims (1)

[Claims] 1. In a serial communication method for transferring serial data from a first device (1) to a second device (2), the serial data is generated in the first device (1). A serial communication method characterized by transmission in synchronization with the generation timing of other variable period signals.