Trying to power on/off esp8266 power with a 2n2222a NPN transistor
Thanks to mkeith &amp; JRE, I finally got the solutions.
There were 2 problems:


voltage drops to 3.2 instead of 3.3 beacause of the NPN transistor. Using a PNP to give the LD1117V33 a real ground fixed it.
serial messages were corrupted because the esp ignored the first message: it didn't have time to wake up between transistor activation, and the first serial message, which goal is to set up the baud speed! Adding a "delay(1000)" fixed the issue.


Thanks a lot!