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#199135
I'm having an issue with my Sparkfun ESP8266 thing dev board:
If I switch off the power supply when the ESP is connected to a Wi-Fi, it won't connect and run when the power is switched on again. I have to cycle the power switch on the board for it to boot correctly.

How can i make it reboot correctly when i toggle the power supply?
#199372
TLDR: Use the switch. It's not a bug, it's a feature.

Removing a power supply connection does not mean that the device runs out of power. There are capacitors that may not drain quickly enough. In this case the voltage regulator has an enable pin with is connected to that switch. If the enable pin is connected to ground (it's voltage becomes less than 0.4 volt) then the output get's drained through a 60 Ohm internal resistor). The on state of that switch connects to the input voltage Vin. That has a capacitor to ground, the reverse voltage protection diode to the USB connector and a 3Mohm internal pulldown resistor in the voltage regulator. The other switch connects the enable pin to ground. So if you do not switch the enable pin to ground with a disconnected supply then the 1 microFarad capacitor has can only drain through the 3 Megaohm resistor and that will take around 300 miliseconds. Unless you have other voltage sources connected to the Vin pin. Do you?

Other than that I remember YouTube videos by Andreas Spiess where he explained that certain radio functions in the ESP8266 did not reset completely after waking up from sleepmodes. I don't know which video exactly. But you should be able to narrow it down with Youtube's search function in this channel. https://www.youtube.com/channel/UCu7_D0 ... pEohoP7YSQ