The TIMER module contains three counters that can be used to provide an operating system time base. While one counter is used as the operating system time base, it is possible to use one of the other counters as a diagnostic on the first, using periodic check via software of the counter values in the two timers. The second counter can be fed with a different clock source and a different prescale configuration can be selected to avoid common mode errors. Error response, diagnostic testability, and any necessary software requirements are defined by the software implemented by the system integrator.