user67502: 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.


user67502: Apparently it's a pretty common issue for people using this board. There are a  couple of solutions here that I will try: https://github.com/IOT-MCU/ESP-01S-Relay-v4.0/issues/1
The most non invasive one with Tasmoto firmware didn't work in my case. So I will try another pin and if that fails, bite the bullet and introduce a capacitor.

user62127: 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.

67502: <p>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.</p>
<p>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.</p>
<p>I need the unit to wake up from deep sleep, and keep the relay in the off position, unless triggered by some external criteria.</p>
<p>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.</p>
<p><a href="https://i.stack.imgur.com/QFNqr.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QFNqr.jpg" alt="ESP01 Module" /></a></p>
 67502: <p>Apparently it's a pretty common issue for people using this board. There are a  couple of solutions here that I will try: <a href="https://github.com/IOT-MCU/ESP-01S-Relay-v4.0/issues/1" rel="nofollow noreferrer">https://github.com/IOT-MCU/ESP-01S-Relay-v4.0/issues/1</a></p>
<p>The most non invasive one with Tasmoto firmware didn't work in my case. So I will try another pin and if that fails, bite the bullet and introduce a capacitor.</p>
 62127: <p>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.
<a href="https://rabbithole.wwwdotorg.org/2017/03/28/esp8266-gpio.html" rel="nofollow noreferrer">https://rabbithole.wwwdotorg.org/2017/03/28/esp8266-gpio.html</a></p>
<p>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.</p>
