Guru
Joined: 11/02/2018
Location: AustraliaPosts: 3213
| Posted: 08:42pm 08 Oct 2025 |
If you replace the MOSFETs with 74HC14 Schmidt inverters Volhout's circuit is almost the same as the one that I was thinking of.
The only difference is an input capacitor (used in previous designs in this thread).
Without it if the Pico freezes during the pulse the DOUT will stay high preventing the RC from timing out.
With it the pulse duration is limited, allowing the RC to trigger a reset in all cases.
The catch is adding the capacitor means timing will start as soon as power is applied.