Semiconductor device that detects abnormalities of watchdog timer circuits
First Claim
1. A semiconductor device comprising:
- a central processing unit (CPU);
a first watchdog timer that monitors a runaway of the CPU;
a second watchdog timer that monitors the runaway of the CPU;
a first diagnosis circuit that monitors the first watchdog timer and generates a first diagnosis result signal; and
a second diagnosis circuit that monitors the second watchdog timer and generates a second diagnosis result signal,wherein the first diagnosis circuit receives the second diagnosis result signal and the second diagnosis circuit receives the first diagnosis result signal, and wherein the first and second diagnosis circuits monitor each other by the first and second diagnosis result signals.
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Accused Products
Abstract
A diagnosis circuit 1 monitors a watchdog timer 2 and supplies a diagnosis result signal 1 indicating whether a monitoring result is normal or not to a diagnosis circuit 2. A diagnosis circuit 3 monitors a watchdog timer 1 and supplies a diagnosis result signal 3 indicating whether a monitoring result is normal or not to the diagnosis circuit 2. The diagnosis circuit 2 determines that the diagnosis circuit 1 or the watchdog timer 2 is abnormal when the diagnosis result signal 1 does not have a value indicating normal. Further, the diagnosis circuit 2 determines that the diagnosis circuit 3 or the watchdog timer 1 is abnormal when the diagnosis result signal 3 does not have a value indicating normal.
8 Citations
8 Claims
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1. A semiconductor device comprising:
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a central processing unit (CPU); a first watchdog timer that monitors a runaway of the CPU; a second watchdog timer that monitors the runaway of the CPU; a first diagnosis circuit that monitors the first watchdog timer and generates a first diagnosis result signal; and a second diagnosis circuit that monitors the second watchdog timer and generates a second diagnosis result signal, wherein the first diagnosis circuit receives the second diagnosis result signal and the second diagnosis circuit receives the first diagnosis result signal, and wherein the first and second diagnosis circuits monitor each other by the first and second diagnosis result signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification