Set up for 115200 baud and nothing.
if you send
AT+RST
you will get a response of,
ets Jan 8 2013,rst cause:4, boot mode:(3,6)
wdt reset
load 0x40100000, len 24444, room 16
tail 12
chksum 0xe0
ho 0 tail 12 room 4
load 0x3ffe8000, len 3168, room 12
tail 4
chksum 0x93
load 0x3ffe8c60, len 4956, room 4
tail 8
chksum 0xbd
csum 0xbd
ready
and
If you tried this from the adaptor 3v3 you would get garbage. Looking at 3v3 on scope it was horrible.
Only to be expected as it turned out to be a zener diode and data sheet said the ESP8266 can take over 200mA.Look at https://nurdspace.nl/ESP8266 for more info.
