A battery-powered wake-up shield for Wemos D1 Mini (ESP8266) that triggers from external events like buttons, switches, or PIR sensors.

• External Wake-up - Wake ESP8266 from deep sleep via button, switch, or PIR sensor
• Ultra-low Power - As low as 7uA standby current (with J1 & J2 cut)
• Flexible Power - 2.5V to 6V input (4xAA, 3.7V LiPo, etc.)
• NO/NC Support - Works with normally open or normally closed switches
• Battery Monitoring - Built-in voltage divider on A0 for VBatt measurement
• Debouncing - Hardware-based button debouncing and retrigger protection
• Plug & Play - Stacks directly on Wemos D1 Mini

Measured at VBatt 3.7V

1. Open Arduino IDE
2. Go to Sketch > Include Library > Manage Libraries...
3. Search for MicroWakeupper
4. Click Install

cd ~/Arduino/libraries
git clone https://github.com/tstoegi/MicroWakeupper.git

#include <MicroWakeupper.h>

MicroWakeupper mw;

void setup() {
    Serial.begin(115200);
    mw.begin();

    if (mw.resetedBySwitch()) {
        Serial.println("Woke up from external trigger!");
    } else {
        Serial.println("Woke up from deep sleep timer");
    }

    // Read battery voltage
    float vbatt = mw.readVBatt();
    Serial.printf("Battery: %.2fV\n", vbatt);

    // Do your work here...

    // Re-enable triggering and go back to sleep
    mw.reenable();
    ESP.deepSleep(60e6); // Sleep for 60 seconds
}

void loop() {
    // Not reached when using deep sleep
}

MicroWakeupper mw(bool disableAtStartup = true, int staPin = D6, int disPin = D7);

Important: resetedBySwitch() uses RTC memory to reliably distinguish between MicroWakeupper triggers, timer wakeups, and hardware resets. For accurate detection, you must call reenable() before ESP.deepSleep(). This saves the current state to RTC memory.

• J1 - Cut to completely power off Wemos (no deep sleep)
• J2 - Cut to disable VBatt measurement (saves ~48uA)

All hardware design files are available in the /pcb directory.

The assembled MicroWakeupper shield is available on Tindie:

• MyMeter - Gas/Water meter reading with MicroWakeupper

An interactive test sketch is included in the /test/InteractiveTest directory. Use it to verify that the MicroWakeupper hardware and library are working correctly.

The ESP8266 cannot natively distinguish between different reset sources (timer wakeup, external trigger, hardware reset button). The MicroWakeupper library uses RTC memory to track state across deep sleep cycles, enabling reliable detection. The test sketch helps verify this works correctly with your hardware.

1. Upload test/InteractiveTest/InteractiveTest.ino to your Wemos D1 Mini
2. Open Serial Monitor at 115200 baud
3. Follow the on-screen instructions

This project is open source hardware and software. See LICENSE for details.

Special thanks to @davedarko for inspiration and support!

Made with care by @tstoegi