We are having trouble understanding the NRST pin characteristics.
The STM32H742xI/G STM32H743xI/G datasheet gives these parameters:
I have three questions:
1. What does 'input filtered' and 'input not filtered' pulse mean?
2. Is it by design true that a filtered reset trigger with a duration shorter than 50ns, will never be detected?
3. We use a 3.3V Vdd. Does a not-filtered pulse require 300ns or 1000ns duration to detect a reset?
1. In this sense, "filtered" means the pulse is filtered out and doesn't produce a reset.
2. Yes. I would test it on your board and in your noise environment if you require this functionality. Noise on the pin can cause spurious resets, hence the recommendation for a decoupling cap close to the NRST pin.
3. Almost assuredly 300ns, despite the ambiguity in the datasheet. Lower voltage (i.e. 1.62 V to 1.71 V) will require a longer pulse.
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.