ESP8266

a microcontroller that implements an entire wifi network stack. can serve as a client, a server and even an access point.

things are moving fast

this document was written with ESP-12E in mind although as far as documentation goes all firmware versions should run on all hardware version

specs

ESP8266EX Datasheet

dev (evaluation) boards

• Adafruit HUZZAH ESP8266 Breakout (preinstalled with NodeMCU)
• SparkFun ESP8266 Thing

basic Connectivity

• VCC -> 3.3V
• EN -> 3.3V
• GND -> GND
• TX -> RX
• RX -> TX

Current can spike above 300mA so use an external power supply!

using ESP8266 - two methods

AT Command Set (original firmware)

custom firmware

working with the AT command Set

The AT commands

<example>

Pyesp8266 (Guy Zyskind) - Python code for wrapping serial AT commands

WeeESP8266 - arduino library for wrapping serial AT commands

custom firmware

• Arduino IDE! - write firmware in C code with the arduino libraries.
• NodeMCU - lua interpreter
• Espruino (alpha) - Javascript interpreter

restoring the AT command set firmware

• esptool - a python flashing firmware tool (cross platform)
• firmaware 0.9.2.2 (if you have access to a newer firmware image - let me know)

To get into boot loader mode set the following pins:

GPIO 0: LOW

GPIO 2: HIGH

GPIO 15: LOW

(if you’re using the huzzah board just press the reset button while pressing the GPIO10 button, let go of the reset button and then let go of the GPIO10 button. the red led should be lit but dimmed).

When in bootloader mode run the following:

$ sudo esptool.py -p <serial_port> write_flash 0x000000 v0.9.2.2_at_firmware.bin

advice for using esp8266 for IoT devices:

• use esp8266 as a client and pull commands from a remote server
• build for sustaining failure
• reduce overhead. use raw tcp/udp for sustainable connections.

Resources

• ESP8266.com - the comprenshive resource for everything esp8266.