ESP8266 Community Forum

If you are using I2C bus, save other pins for important things, and use GPIO2/GPIO0 for I2C since the bus also need PullUps, they are perfect match with the Boot process without any conflicts.

martinayotte wrote:

d1414213562 wrote:Still no program is left in flash after power is disconnected.

I don't think the Flash is emptied at all. I'm still convince that it is a Boot mode issue where GPIO2/GPIO0 are not HIGH when power is recycled, for some unknown reason.

Thanks, this solved my issue! I was assuming it would work more like an Arduino on a NodeMCU board, and that I didn't have to mess with resistors as it already has a flash button integrated. But now I put 2 10k resistors with 3.3v on 1 end and GPIO0 and 2 (D3 and D4 on my board) on the other end and it works, great!