This module will wake an ESP8266 from deep sleep when a sensor value changes (e.g. push button, float sensor, or other reed sensor).
Disclaimer: If you need to do this, then you should probably use a different MCU that supports deep sleep interrupt on edge. But, if like me, you bought many ESP8266s and want to use them in a project where you have this requirement...
Connect input to the sensor, and output to the RST pin on the ESP8266.
Note: Above is Rev 1 (latest is Rev 1a)
When the input changes (goes from high to low or low to high), a short pulse is generated on the output which wakes the ESP8266 from deep sleep.
Note: The blue line above is mis-labeled as Q1, and should read Q3.
Either circuit A or B can be used. A is a dual edge monostable trigger, and B is an edge to glitch conveter (XOR with delay). Solder the circuit jumper to choose between circuit A or B (the center pad is the input).
For circuit A, solder either the leading or falling jumper (or both can be soldered to pulse on both edges). For circuit B, a pulse will always be generated on both edges.
VCC min 2.5 V, max 6.0 V.
Example use case: Wake your ESP8266 and report a float sensor value change (e.g. when a water tank is full).
Note: Resistor bodge was needed for board Rev 1 (now obsolete, replaced by Rev 1b which fixed the issue).