Question regarding the Watchdog Timer on the device. See the excerpt from BS EN50271 standards below, which requires the following for fire safety systems:
Monitoring equipment with its own time base (e.g. watchdog) shall work independently and separately from the parts of the digital unit which perform the data processing. Triggering of the monitoring equipment (e.g. watchdog) shall be based on the program execution and shall not be only time-related (e.g. based on a periodic timer interrupt);
Independent operation is considered to be fulfilled if:
- The operation of the monitoring equipment (watchdog) cannot be controlled by the digital unit which performs the data processing (CPU)
- The voltage supply is separately connected to the power supply of the digital unit.
- Negative effects (e.g. ESD, EMC) on the operation of the data processing unit (CPU) are not likely to influence the operation of the monitoring equipment (watchdog)
- malfunction of the data processing unit (CPU) caused by thermal or electrical overload will not influence the operation of the monitoring equipment
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The question is this: the watchdog in the F1232 is a separate hardware module that runs on ACLK (according to the datasheet). Is the watchdog's operation considered "independent" from the CPU per any of the guidelines above?