Operation Of I/O In A Safe System

摘要

A module health system includes a module health circuit comprising a hardware register that is set to a first value in response to the system starting, an application register that is set to the first value in response to the system starting and a watchdog timer register that is set to the first value in response to the system starting. The system further includes a power on self-test that determines whether the system has passed a plurality of tests and that selectively sets the hardware register to a second value based on the determination, an external software application that determines whether a safety critical system is healthy and selectively sets the application register based on the determination, a watchdog timer application that selectively sets the watchdog timer register, a central processing unit that determines whether to de-assert a module health signal.

主权项

1. A module health system comprising:
a module health circuit that includes: a first hardware (HW) register that is set to a first value in response to the system starting; a first application register that is set to the first value in response to the system starting; a first watchdog (WD) timer register that is set to the first value in response to the system starting; a first power on self-test (POST) that determines whether the system has passed a plurality of tests and that selectively sets the first HW register to a second value based on the determination; an external software application that determines whether a safety critical system is healthy and selectively sets the first application register based on the determination; a watchdog timer application that selectively sets the first WD timer register in response to receiving a watchdog signal; and a first central processing unit (CPU) that determines whether to de-assert a first module health signal based on a value of the first HW register, the first application register, and the first WD timer register.