JPH02281367A - Sate reproducing method - Google Patents

Abstract

PURPOSE:To restore a normal state with an inexpensive constitution by transferring data indicating the operation state from a main CPU to a sub-CPU at intervals of a prescribed time and reproducing the normal state before restart based on the data by the sub-CPU at the time of restart with respect to the state reproducing method for restart after runaway of a microcomputer. CONSTITUTION:A system consists of a main CPU 1 which performs a prescribed processing by the request from a sub-CPU 2, the sub-CPU 2 which detects a key input to transfer key data to the CPU 1 and receives the command sent from the CPU 1 to control the display, a serial transmission line 3, a key part 4, an LED 5 on which the operation mode is displayed, an encoder 6, a display driver 7, and a watchdog timer 8. In this constitution, a pulse PS is outputted to the timer 8 at intervals of a prescribed period when the CPU 2 is normally operated, but the pulse PS is not outputted and a reset signal RSS is outputted to initialize the CPU 2 when the CPU 2 runs away.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a state reproduction method, and particularly to a state reproduction method at the time of restarting a microcomputer after a runaway.

<Prior art> A CPU that performs main processing (main CPU) and a sub CPU that performs predetermined operations based on instructions from the main CPU
There is a system in which data is exchanged between these two CPUs based on a serial I10 interface, and desired processing is executed as a whole.

In such a system, for example, the sub CPU detects key human power and informs the main CPU of the key human power, and the main CPU executes a predetermined process based on the key human power, and also sends a predetermined command to the sub CPU. C.P.
Based on the command, U performs on/off control of the display element, etc., and displays the operating state of the main CPU.

By the way, the sub CPU may run out of control due to some kind of disturbance. When such runaway is detected by a watchdog timer etc., the sub CPU is reset,
Restart the program from the beginning. At this time, each output terminal on the sub CPU side is set to the initial value, reproducing the normal state before restart (displaying the operating state, etc.)
For example, if the main CPU is performing processing according to a predetermined mode, the sub CPU side will display a display according to that mode, but since it will be initialized when restarting after detecting a runaway, Unable to display mode.

For this reason, conventionally, a non-volatile memory is provided on the sub-CPU side, the current operating state is stored in the non-volatile memory (backup), and when the sub-CPU is restarted due to runaway detection, etc., the storage contents of the non-volatile memory are The state before the restart is reproduced by referring to , so that the operating state of the main CPU and the state (for example, display state) on the sub CPU side are made to match even after the restart.

<Problems to be Solved by the Invention> However, this conventional method requires a non-volatile memory and processing for backing up the current state to the non-volatile memory, making the configuration complex and expensive, and the time required until runaway detection is The contents of non-volatile memory change under the influence of external disturbances,
There is a problem that a contradiction occurs between the main CPU and the sub CPU.

From the above, it is an object of the present invention to provide a state reproduction method that can accurately reproduce the state before rebooting without providing a nonvolatile memory.

Means for Solving the Problems> The above problems are solved in the present invention by means of transmitting data indicating the current operating state from the main CPU to the sub CPU at predetermined intervals, and by means of transmitting data from the main CPU to the sub CPU at predetermined intervals. This is achieved by means of reproducing the normal state before restart in the sub CPU based on the data received.

Function> When the processing operation mode changes due to key operation, etc., the main CPU sends predetermined data to the sub CPU side,
The PU controls mode display etc. based on the data.
In addition, the main CPU transfers a command indicating the current operating state to the sub CPU at predetermined intervals, and this causes the sub CPU to
When the U is restarted after detection of runaway, etc., it reproduces the normal state (mode display, etc.) before the restart based on the command sent from the main CPU.

<Embodiment> Fig. 1 is a block diagram of a system to which the present invention can be applied, in which 1 is a main CPU that performs predetermined processing based on requests from the sub-CPU side, and 2 is a main CPU that detects key human power and transfers key data to the main CPU. a sub-CPU that transfers commands to the CPU and receives commands sent from the main CPU to control display, etc.;
3 is a serial transmission line, 4 is a key part, 5 is a display unit equipped with an LED (light emitting diode), etc. that displays the operation mode and other statuses, 6 is an encoder that outputs a code according to the pressed key, 7 is a display driver, and 8 is a watchdog timer.

In the main memory l, 11 is a timer, 12 is a memory that stores the latest operating status of the main CPU, etc.
In the case of an automobile navigation system, (1) the current operating state, (2) the current display scale level.

(3) The power on/off status of the CRT that displays the map, etc. is stored. The operating states include a current vehicle position display mode, a route setting mode to a destination, and a map search mode. The main CPU 1 stores the latest operating status etc. in the memory 12, and transfers commands (data) indicating the status to the sub CPtJ2 at predetermined intervals.

Runaway of sub CPU 2 is detected by watchdog timer 8. That is, during normal operation, the sub CPU 2 outputs a pulse PS to the watchdog timer 8 at a predetermined period. For this reason, the count value of a clock counting counter (not shown) with a built-in watchdog timer is reset each time an overflow pulse (reset signal R85
) is not output. However, if the sub CPU 2 goes out of control, the pulse PS cannot be output, and therefore an overflow pulse, that is, a reset signal R5S is generated from the counter, and the runaway is detected. Furthermore, the sub-C is activated by the reset signal R8S.
PU2 is initialized.

FIG. 2 is a time chart showing the processing of the present invention. When the sub CPU 2 goes out of control and the pulse PS is no longer generated at time ti, the watchdog timer 8 changes the pulse PS to time t.
3, a reset signal R85 (low level) is generated. As a result, sub CPU2 is initialized,
Thereafter, the process is repeated from the beginning of the program, but at time t3
On/off control such as status display is performed based on commands (serial I10 data) indicating operating status etc. sent from the main CPUI.

FIG. 3 is a flowchart of the processing of the main CPU.

The main CPU monitors whether key data has been input (step 101), and when a key operation is performed, the sub CPU
When a code corresponding to the key is sent from U2, processing according to the key code is started and a predetermined command is sent to the sub CPU 2 (step 102). command, and a command to generate a buzzer sound to confirm receipt of the key code.

Next, the main CPUI stores or updates the current operating state in the memory 12 and continues processing (steps 103 and 104).

In parallel with this process, it is monitored whether a predetermined period of time has elapsed (step 1o5), and if "NO", step 1
01 and subsequent steps are repeated, and if a predetermined period of time has elapsed, a command indicating the latest operating state stored in the memory 12 is transferred to the sub CPU 2 (Step 106), Step 1
The process from step 01 onward is repeated. If no key data is input in step 101, the process jumps to step 104 and continues the process according to the latest key manual data.

Thereafter, the above process is repeated, and the latest operating state is transferred from the main CPUI to the sub CPU 2 at predetermined intervals.

In such a state, when the sub CPU 2 goes out of control and the pulse PS is no longer generated at time t (see FIG. 2), a reset signal R8S (low level) is generated from the watchdog timer 8 at time t2, and the sub CPU 2 is initialized.

As a result, the sub CPU 2 restarts (repeating the process from the beginning of its own program), and if the runaway has stopped, the time 1. in FIG. 2 is reached. At step 106 in FIG. 3, on/off control of various displays is performed based on the command indicating the operating state transferred from the main CPUI, and the states of the main CPU and sub CPU are made to match.

<Effects of the Invention> According to the present invention, data indicating the operating state is transferred from the main CPU to the sub-CPU at predetermined intervals, and upon restart, the sub-CPU is transferred based on the data sent from the main CPU. Since the system is configured to reproduce the normal state before restart, there is no need to provide a non-volatile memory for backup processing, and therefore the state before restart can be reproduced with an inexpensive and simple configuration.

Further, according to the present invention, since the operating state is received from the main CPU, the states of the main CPU and the sub-CPU can be accurately matched.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a system that realizes the present invention. Figure 2 is a time chart of the present invention; FIG. 3 is a flowchart of the process of the present invention. 1. Main CPU 2...Sub CPU 4.Ki part 5.Display section 8.Watchdog timer 11...Timer 12...Memory for state storage

Claims (1)

[Claims] In a state reproduction method for a system including a main CPU and a sub CPU, the main CPU transfers data indicating the current operating state to the sub CPU at predetermined intervals, and the sub CPU transfers data indicating the current operating state at predetermined intervals, and the sub CPU A state reproduction method characterized by reproducing a normal state before restart based on the data sent from the main CPU.