How to prevent flickering relay upon waking from deep sleep using ESP01 board? I have a cheap ESP01 relay module and am using it with ESPEasy. I soldered the GPIO pin 16 to RST to allow deep sleep and that all works great.
However when the unit wakes up the relay flickers quite a bit. The application I had in mind was for a 12v fridge which draws quite a bit of current on start up. I think this flickering would damage the fridge compressor or controller pretty quickly, not to mention wearing out the relay itself.
I need the unit to wake up from deep sleep, and keep the relay in the off position, unless triggered by some external criteria.
Perhaps a capacitor would absorb the pin high voltage for a short period until it's booted? Trouble is that I don't really want to hack the module, I'll probably break something.
The only two pins that don't glitch or change state during reset and boot are GPIO4 and GPIO5, and neither of them are brought out to the 2x4 header on an ESP-01.
https://rabbithole.wwwdotorg.org/2017/03/28/esp8266-gpio.html
All of the other pins will make your relay click or chatter.  Pick a different module, or try soldering a wire onto GPIO4 or 5. The boot time is ~ 150ms long, so it'd take a long time constant R-C circuit to filter it out, on the order of 1/2 second or more.