I use a ESP-12E, where all the pins are broken out and nothing is connected on the board itself.
Online I found different ways to connect the pins GPIO16 and RST (RESET) to allow automatic wake-up from deep sleep:
- direct connection (https://jeelabs.org/book/1526b/ and https://www.losant.com/blog/making-the-esp8266-low-powered-with-deep-sleep)
- low-pass filter with capacitor between the pins and resistor between RST and Vcc (https://www.letscontrolit.com/forum/viewtopic.php?t=2320)
I also found someone using CH_PD ("EN") pin instead of RST, but I see it's not the preferred way.
What are the differences between the two alternatives I listed?
Best Answer
Most of the people face the problem while connecting them. The issue is that GPIO16 provides a strong HIGH during deepSleep and your external reset from Serial-TTL is fighting to make a reset, but loosing, the GPIO16 is the strongest. To avoid such issue, simply replace the wire by a 470R or 1K between GPIO16 and RES, which will allow the Serial-TTL to win. (you can also use a schottky diode with the cathode on GPIO16 side)