Power cycle the ESP8266 with GPIO0 grounded (clean power application, see below).Check you have selected a COM port in the Arduino Tools menu.Check you have ESP8266 board selected in the Arduino Tools menu.In that case follow these steps to get it working:. When programming the ESP8266 using the Arduino IDE (see ESP8266-01 Wifi Shield) you sometimes (often) get an error messages in the Arduino IDE like esp_com open failed error: Failed to open COM33 error: espcomm_open failed error: espcomm_upload_mem failed

ESP8266 Programming Tips (espcomm failed) GPIO6-GPIO11 also require special treatment as described below. These GPIO's control how the module starts up and as such require special handling if they are to be used at all. Most modules, other than ESP8266-01, also make GPIO15 accessible. All modules make GPIO0 and GPIO2 accessible. It comes in a variety of module types and can be programmed in a variety of ways.

Update: Also check out How to use the ESP8266-01 pinsĪlso see ESP32 / ESP8266 Auto WiFi Config for Beginners for a simple way to connect your ESP to any local network, without re-programming.ĮSP8266 is a low cost wifi enabled chip. This is a very short note on how to use GPIO0 / GPIO2 and GPIO15 pins on the ESP8266 module. Updated 24th December 2021 – added note on preventing GOIO0 relay flicker on startup Update 1st July 2018 - Added note on re-programming when GPIO0 is an output

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