Watchdog signal handle

[Fasching_K]

Hello everybody,

I have a question about a reading a signal with a digital input. I would like to handle a watchdog signal that I get from a higher level system. The watchdogs signal works like a heartbeat. Is there a failure with the system in the higher level my system should notice that. The watchdog signal is a square-wave-signal (0,1,0,1 etc.). At the moment I do not now the frequency. The plan is that when the signal stands by 0 or 1 to wait two seconds. If there is no reaction after two seconds the program should stop because the high level system has an error.

Has someone a idea how I can implement this feature? For me it is important to know how I can do the signal acquisition correct.

Best regards

[Fasching_K]

I forgot to mention that the acquisition should not use to much from the CPU. At the moment that is my main problem.

Best regards

[Duffy2007 · Accepted solution]

Hello Fasching_K,

depending on the hardware change detection can be an option, or using one counter for a frequency measurement, or simple read the dio hardware timed in and made an analysis over the acquired Signal, or using an analog input with an fft function behind.