Have you ever wondered how to turn on ESP8266 using external interrupt? Build a battery powered amazon dash button or a 18650 lipo powered door bell using ESP8266 without putting the device in deep sleep? Here is your answer.

Idea

  1. Keep ESP8266 on OFF mode as default
  2. External 3.3V signal (can be short or long) arrives and turns ON ESP8266
  3. ESP8266 wakes up and keeps itself awake until a task is perfomed
  4. Send MQTT data to server
  5. Put ESP8266 back to power OFF state

Implementation

  1. RST pin is always HIGH/3.3V using 10k resistor
  2. ESP8266 is in OFF state, GPIO0 is low
  3. 3.3V signal arrives externally, GPIO0 and CH_PD are high, turn ON ESP8266
  4. First thing ESP8266 does is turns GPIO0 to high, which means CH_PD remain high. So ESP8266 remains ON until GPIO0 is high
  5. GPIO12 is used to read value of external interupt
  6. If there is 3.3V external interrupt, GPIO is high and a MQTT message is sent as “Signal Received” or “ON” and keep ESP8266 ON until 0V signal is received.
  7. If there is 0V external interrupt, GPIO0 goes low and MQTT message is sent as “Signal Vanished” or “OFF” and turns OFF ESP8266

Software

This project is built using ideas at http://www.esp8266.com/viewtopic.php?f=11&t=4458

Github: debsahu/ESP_External_Interrupt

Build

Build