JP2007226527A - Controller and watchdog timer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately reset a CPU even when abnormality occurs while a CPU is performing start processing. <P>SOLUTION: The watchdog timer performs timekeeping by a start processing timer separately from timekeeping by a normal operation timer. When the abnormality occurs while the CPU is performing the normal operation and, due to an occurrence of the abnormality, it is detected that the normal operation timer monitoring time has passed before a next watchdog kick signal is inputted, a reset signal is outputted to the CPU. Also, when the abnormality occurs while the CPU is performing the start processing and, due to an occurrence of the abnormality, it is detected that the start processing timer monitoring time has passed before the CPU normally completes the start processing, the reset signal is outputted to the CPU again. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device and a watchdog configured such that the control means outputs a watchdog kick signal to the watchdog timer and the watchdog timer outputs a reset signal to the control means to reset the control means. Regarding timers.

As a configuration for determining whether or not an abnormality has occurred while the CPU is performing normal operation, the CPU outputs a watchdog kick signal to the watchdog timer. Every time it detects that a signal has been input, it stops and restarts the time counting by the timer, and when it detects that the timer monitoring time has passed before the next watchdog kick signal is input from the CPU (timer has timed up), In general, it is determined that an abnormality has occurred when the CPU is performing normal operation, and a reset signal is output to the CPU to reset the CPU (hardware reset) (see, for example, Patent Document 1).
JP 2005-151032 A

  By the way, the timer monitoring time for determining the output timing of the reset signal is assumed that the processing of one unit in the normal operation ends normally as shown in FIG. 6 in consideration of the state in which the CPU is executing the normal operation. In general, a longer time (for example, a time that is 1.5 to 2 times longer than a time when one unit of processing is estimated to end normally) is determined as the normal operation timer monitoring time. On the other hand, when the power is turned on or reset, the CPU executes a start-up process from when the power is turned on or reset until the normal operation is started. Outputs a watchdog kick signal to the watchdog timer even when a startup process that does not require outputting a watchdog kick signal is being executed.

  However, in the configuration in which the watchdog kick signal is output to the watchdog timer when the CPU is executing the startup process, even if an abnormality occurs while the CPU is executing the startup process, the CPU Since the signal output continues, it becomes difficult for the watchdog timer to output a reset signal to the CPU, and it becomes difficult to reset the CPU. Such a problem can be solved by determining the timer monitoring time regardless of the state in which the CPU is performing the normal operation. When an abnormality occurs, a new problem arises that it is difficult to properly reset the CPU.

  The present invention has been made in view of the above-described circumstances, and its purpose is to appropriately reset the control means when an abnormality occurs while the control means is performing normal operation. An object of the present invention is to provide a control device and a watchdog timer which can appropriately reset the control means even when an abnormality occurs while the means is executing the startup process, and can improve the reset accuracy.

  According to the control device of the first aspect, when the power is turned on or reset, the control means performs a start-up process from the time when the power is turned on or reset until the transition to the normal operation. The output to the watchdog timer is stopped, and when the normal operation is executed after shifting to the normal operation, the watchdog kick signal is output to the watchdog timer. The watchdog timer starts timing by the activation process timer from the time when the power is turned on or a reset signal is output to the control means, and the control means has successfully completed the activation process before the activation process timer monitoring time elapses Is detected at the timing when the control means shifts to the normal operation, the time measurement by the start processing timer is terminated and the time measurement by the normal operation timer is started. Thereafter, the control means is executing the normal operation from the control means. Every time it is detected that the watchdog kick signal has been input, the time measurement by the normal operation timer is terminated and restarted, and the normal operation timer monitoring time has elapsed before the next watchdog kick signal is input from the control means. When detected, a reset signal is output to the control means. In addition, when the watchdog timer detects that the activation process timer monitoring time has elapsed before the control means normally ends the activation process, it outputs a reset signal to the control means.

  Therefore, the time measured by the activation processing timer and the time measured by the normal operation timer are separately performed, and an abnormality occurs while the control means is executing the normal operation. When it is detected that the normal operation timer monitoring time has elapsed before the watchdog kick signal is input, the reset signal is output to the control means. Even in this case, the control means can be appropriately reset.

  In addition, an abnormality occurs during execution of the startup process from when the control unit is turned on or reset to the transition to normal operation, and the control unit normally ends the startup process due to the occurrence of the abnormality. In this case, since it is configured to output the reset signal to the control means when it is detected that the start processing timer monitoring time has passed before, the control means is in the case where an abnormality occurs while executing the start processing. However, the control means can be appropriately reset.

  As a result, when the abnormality occurs during the normal operation of the control means, the control means is reset appropriately, as well as the control means when the abnormality occurs while the control means is executing the startup process. It is possible to appropriately reset, and the accuracy of reset can be increased.

  According to the control device described in claim 2, the control means is the same as the watch dog kick signal output to the watch dog timer in the subsequent normal operation at the timing when the startup process is normally terminated and the normal operation is started. The watchdog kick signal is output to the watchdog timer. After the power is turned on or the reset signal is output to the control means, the control means normally inputs the first watchdog kick signal from the control means, and the control means normally starts. It detects that it was finished.

  As a result, the control means has successfully completed the start-up process without any improvement in the configuration of outputting the watchdog kick signal from the control means to the watchdog timer and outputting the reset signal from the watchdog timer to the control means. A watchdog timer can detect.

  According to the control device of the third aspect, the control means is a timing at which the startup process is normally terminated and the normal operation is started, and the watchdog kick signal output to the watchdog timer in the normal operation thereafter A different normal start signal is output to the watchdog timer. After the power-on or reset signal is output to the control means, the watchdog timer inputs the normal start signal from the control means, and the control means ends the start processing normally. Detect the effect.

  As a result, the control means distinguishes from the watchdog kick signal the normal start signal that is output when the control means normally ends the start process and shifts to the normal operation, thereby confirming that the control means has normally ended the start process. The dog timer can be reliably detected.

  According to the watchdog timer of the fourth aspect, the clocking by the activation process timer is started from the time when the power is turned on or the reset signal is output to the control means, and the control means is activated before the activation process timer monitoring time elapses. When the startup process is completed normally, the timing by the startup process timer is terminated at the timing when the control means shifts to the normal operation, the time measurement by the normal operation timer is started, and the control means is executing the normal operation. Each time it is detected that the watchdog kick signal has been input from the timer, the clocking by the normal operation timer is stopped and restarted, and the normal operation timer monitoring time has elapsed before the next watchdog kick signal is input from the control means. Is detected, a reset signal is output to the control means. Further, when the control means detects that the start process timer monitoring time has passed before the start process is normally completed, a reset signal is also output to the control means in this case.

  As a result, in the same manner as described in claim 1, the control means can appropriately reset the control means when an abnormality occurs while the control means is performing normal operation. Even when an abnormality occurs during execution, the control means can be appropriately reset, and the reset accuracy can be improved.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a control device mounted on an in-vehicle emergency call device will be described with reference to FIGS. 1 to 3. As shown in FIG. 3, the control device 1 includes a CPU (control means in the present invention) 2 and a watchdog timer (WD timer) 3. The CPU 2 is configured to be able to output a watchdog kick signal (WD kick signal) to the watchdog timer 3, and the watchdog timer 3 is configured to be able to reset the CPU 2 by outputting a reset signal to the CPU 2. Moreover, since the control apparatus 1 is mounted in a vehicle-mounted emergency call apparatus, it is comprised so that the electric power supplied from a vehicle-mounted battery may operate | move as operating power.

  When the power is turned on or reset, the CPU 2 executes a startup process from the time when the power is turned on or reset to the transition to the normal operation. When the startup process ends normally, the CPU 2 shifts from the startup process to the normal operation. It is configured to perform normal operations. Here, the startup process is a process corresponding to preparation for executing a normal operation such as a check of a memory area used when executing a normal operation, and the normal operation is, for example, an in-vehicle emergency call device. In such a case, the operation waits for the input of an airbag detection signal from the airbag ECU.

  The watchdog timer 3 is configured to be able to measure time separately by two timers, a start processing timer and a normal operation timer. In this case, the startup process timer monitoring time until the startup process timer expires is longer than the time that the startup process is expected to end normally (for example, the time that the startup process is expected to end normally). 1.5 to 2 times longer) than the normal operation timer monitoring time. Also, the normal operation timer monitoring time until the normal operation timer expires is longer than the time that one unit of processing in normal operation is expected to end normally (for example, one unit of processing ends normally). Then, the estimated time is 1.5 to 2 times the estimated time.

Next, the operation of the above configuration will be described with reference to FIG. 1 and FIG. Here, FIG. 1 shows the operations of the CPU 2 and the watchdog timer 3 as a time chart, and FIG. 2 shows the operations of the watchdog timer 3 as a flowchart.
When the operating power is supplied from the in-vehicle battery and the power is turned on (when the power is turned on), the CPU 2 executes a startup process. When the watchdog timer 3 is supplied with operating power from the on-board battery and is turned on (when the power is turned on), the watchdog timer 3 starts timing by the activation processing timer (step S1) and receives a watchdog kick signal from the CPU 2 (Step S2) and whether or not the activation processing timer monitoring time has elapsed (step S3).

  Here, when the startup process is normally completed, the CPU 2 outputs a watchdog kick signal to the watchdog timer 3 at the timing of shifting from the startup process to the normal operation. If it is detected that the watchdog kick signal has been input from the CPU 2 before the elapse of time ("YES" in step S2), the clocking by the start processing timer is terminated (step S4), and the clocking by the normal operation timer is started. (Step S5). The watchdog timer 3 monitors whether or not the next watchdog kick signal is input from the CPU 2 (step S6) and monitors whether or not the normal operation timer monitoring time has elapsed (step S7). .

  Now, after the CPU 2 shifts from the startup process to the normal operation, if the normal operation is normally executed (if no abnormality occurs), the next watchdog is displayed before the normal operation timer monitoring time elapses. Since the kick signal is output to the watchdog timer 3, the watchdog timer 3 detects that the next watchdog kick signal is input from the CPU before the normal operation timer monitoring time elapses (" YES ”), the time measurement by the normal operation timer is terminated and restarted (returned to the initial value and started from the beginning, so-called clear) (step S8), the process returns to the above step S6, and steps S6 and S7 are repeated.

  On the other hand, if an abnormality occurs during the normal operation, the CPU 2 cannot output the next watchdog kick signal to the watchdog timer, and the watchdog timer 3 receives the next watchdog kick signal from the CPU 2. When it is detected that the normal operation timer monitoring time has elapsed before the input (the normal operation timer has expired) ("YES" in step S7), a reset signal is output to the CPU 2 to reset the CPU 2 ( Step S9). Then, the watchdog timer 3 finishes the time measurement by the normal operation timer (step S10), returns to the above step S1, and repeatedly executes step S1 and subsequent steps.

  When an abnormality occurs during the normal operation of the CPU 2 by such a series of processes, the watchdog timer 3 indicates that the normal operation timer monitoring time has elapsed before the next watchdog kick signal is input from the CPU 2. And a reset signal is output to the CPU 2 to reset the CPU 2.

  On the other hand, the CPU 2 may output a watch dog kick signal to the watch dog timer without transitioning from the startup process to a normal operation if an abnormality occurs during the startup process and the process does not end normally. Therefore, the watchdog timer 3 detects that the activation process timer monitoring time has elapsed (the activation process timer has expired) before inputting the watchdog kick signal from the CPU 2 ("YES" in step S3). In this case as well, a reset signal is output to the CPU 2 to reset the CPU 2 (step S11). The watchdog timer 3 finishes and restarts the time counting by the activation processing timer (returns to the initial value and starts from the beginning, so-called clear) (step S12), returns to the above step S2, and repeats steps S2 and S3. And execute.

  By such a series of processing, when an abnormality occurs while the CPU 2 is executing the startup processing, the watchdog timer 3 detects that the startup processing timer monitoring time has elapsed before inputting the watchdog kick signal from the CPU 2. Then, a reset signal is output to the CPU 2 to reset the CPU 2.

  As described above, according to the first embodiment, in the watchdog timer 3, the time measurement by the activation processing timer and the time measurement by the normal operation timer are separately performed, and an abnormality occurs while the CPU 2 is executing the normal operation. When a normal operation timer monitoring time elapses before the next watchdog kick signal is input from the CPU 2 due to the occurrence of the abnormality, a reset signal is output to the CPU 2, and If an abnormality occurs while the CPU 2 is executing the startup process, and the CPU 2 detects that the startup process timer monitoring time has elapsed before the CPU 2 normally ends the startup process due to the occurrence of the abnormality, in this case However, since the reset signal is output to the CPU 2, the CPU 2 is appropriately reset when an abnormality occurs while the CPU 2 performs the normal operation. Of course the, CPU2 it is possible to appropriately reset the CPU2 even when an abnormality occurs during the startup process, it is possible to improve the accuracy of the reset.

In particular, the control device 1 installed in the in-vehicle emergency call device as in the present embodiment is activated in comparison with the situation that the power of the in-vehicle battery having a finite power capacity operates as the operating power and the power consumption required for normal operation. Considering the fact that the power consumption required for processing is much larger, it is possible to properly reset the CPU 2 when an abnormality occurs during execution of the startup process.
The effect is great in terms of reducing the power consumption of the entire control device 1 and extending the life of the in-vehicle battery.

  In this case, the watchdog timer 3 detects that the CPU 2 has successfully completed the start-up process by inputting the first watchdog kick signal from the CPU 2 after outputting the power-on or reset signal to the CPU 2. Since the CPU 2 outputs the watch dog kick signal to the watch dog timer 3 and outputs the reset signal from the watch dog timer 3 to the CPU 2 without any improvement, the CPU 2 has successfully completed the startup process. Can be detected by the watchdog timer 3.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, description is abbreviate | omitted about the same part as above-mentioned 1st Embodiment, and a different part is demonstrated.
In the first embodiment described above, the CPU 2 is configured to output a watchdog kick signal to the watchdog timer at the timing of transition from the startup process to the normal operation when the startup process ends normally. In the embodiment, the CPU 12 outputs a normal activation signal, which is different from the watchdog kick signal, to the watchdog timer 13 when the activation process is normally terminated in the CPU 12 at a timing when the activation process shifts to the normal operation.

  That is, in the control device 11, the CPU 12 is configured to be able to output a watchdog kick signal and a normal activation signal to the watchdog timer 13, and the watchdog timer 13 can reset the CPU 12 by outputting a reset signal to the CPU 12. It is configured. In this case, when the startup process ends normally, the CPU 12 outputs a normal startup signal to the watchdog timer 13 at the timing when the startup process shifts to the normal operation, and the watchdog timer 13 passes the startup process timer monitoring time. If it is detected that a normal activation signal has been input from the CPU 12 before the start, the timing by the activation processing timer is terminated and the timing by the normal operation timer is started.

  As described above, according to the second embodiment, in the watchdog timer 13, after a power-on or reset signal is output to the CPU 12, a normal start signal different from the watchdog kick signal is input from the CPU 12. Since the CPU 12 is configured to detect that the startup process has been completed normally, by distinguishing the normal startup signal output at the timing when the CPU 12 ends the startup process normally and shifts to the normal operation from the watchdog kick signal, The CPU 12 can reliably detect that the startup process has been completed normally.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be modified or expanded as follows.
The configuration is not limited to the configuration applied to the control device mounted on the in-vehicle emergency call device, but may be configured to be applied to a control device mounted in another in-vehicle device such as an in-vehicle navigation device or an in-vehicle hands-free device, The configuration may be applied to a control device mounted on a device other than the in-vehicle device (for example, a mobile phone or a communication device).
You may apply to the structure by which the watchdog timer is incorporated in CPU.

The time chart which shows the 1st Embodiment of this invention and shows operation | movement of CPU and operation | movement of a watchdog timer Flow chart showing operation of watchdog timer Functional block diagram The time chart which shows the 2nd Embodiment of this invention and shows operation | movement of CPU and operation | movement of a watchdog timer. 3 equivalent figure Time chart showing the operation of the CPU and the watchdog timer

Explanation of symbols

  In the drawings, 1 is a control device, 2 is a CPU (control means), 3 is a watchdog timer, 11 is a control device, 12 is a CPU (control means), and 13 is a watchdog timer.

Claims (4)

A control device comprising: control means capable of outputting a watchdog kick signal to a watchdog timer; and a watchdog timer capable of resetting the control means by outputting a reset signal to the control means,
The control means stops the output of the watchdog kick signal to the watchdog timer during execution of the start-up process from power-on or reset to transition to normal operation, and watchdog kick during normal operation. Signal to the watchdog timer
The watchdog timer starts timing by the activation process timer from the time when the power is turned on or the reset signal is output to the control means, and the control means normally starts the activation process before the activation process timer monitoring time elapses. When it is detected that the control unit has finished, the time measured by the activation processing timer is terminated at the timing when the control unit shifts to the normal operation, the time measurement by the normal operation timer is started, and the control unit is executing the normal operation. Each time it is detected that a watchdog kick signal has been input from the control means, the time measurement by the normal operation timer is ended and restarted, and the normal operation timer is monitored before the next watchdog kick signal is input from the control means. When it is detected that the time has elapsed, a reset signal is output to the control means, and the control means ends the startup process normally. Even when detecting that has elapsed starting process timer monitoring time ago, control unit and outputs a reset signal to the control unit. The control device according to claim 1,
The control means sends the same watchdog kick signal as the watchdog kick signal output to the watchdog timer in the normal operation thereafter to the watchdog timer at a timing at which the startup process is normally terminated and the normal operation is started. Output,
The watchdog timer detects that the control means has successfully completed the start-up process by inputting a first watchdog kick signal from the control means after outputting a power-on or reset signal to the control means. A control device characterized by. The control device according to claim 1,
The control means sends a normal start signal to the watchdog timer that is different from the watchdog kick signal that is output to the watchdog timer in the subsequent normal operation at the timing when the start process ends normally and shifts to the normal operation. Output,
The watchdog timer is characterized in that after a power-on or reset signal is output to the control means, a normal activation signal is input from the control means to detect that the control means has successfully completed the activation process. Control device. Control that is configured to stop the output of the watchdog kick signal during execution of the startup process from when the power is turned on or reset to transition to normal operation, and to output the watchdog kick signal during execution of normal operation A watchdog timer constituting a control device together with means,
The timing by the activation process timer is started from the time when the power is turned on or the reset signal is output to the control means, and it is detected that the activation means has successfully completed the activation process before the activation process timer monitoring time elapses. In such a case, the timing by the activation processing timer is terminated at the timing when the control means shifts to the normal operation, and the time measurement by the normal operation timer is started. Every time it is detected that a dog kick signal has been input, the normal operation timer is stopped and restarted, and the normal operation timer monitoring time has elapsed before the next watch dog kick signal is input from the control means. When detected, a reset signal is output to the control means, and the start-up process timer is monitored before the control means ends the start-up process normally. Even if but it is detected that the elapsed, the watchdog timer and outputs a reset signal to the control unit.

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