ThermoTimer

Battery-powered thermocouple temperature alarm built on an M5Stack CoreInk (ESP32 + e-paper) with the M5Unit KMeterISO.

Photos

ThermoTimer active	ThermoTimer in sleep mode

Features

• K-type thermocouple readout (°C) via KMeterISO
• On-device target temperature alarm (adjustable in 0.5°C steps)
• E-paper status screen (battery %, current temp, target temp)
• Automatic timed sleep between measurements for long battery life
• Auto power-off after cooldown / idle timeout
• Persists the target temperature in NVS (Preferences)

Hardware

• M5Stack CoreInk
• M5Unit KMeterISO (I²C)
• K-type thermocouple probe
• Optional: M5ThermoTimer_case.scad (OpenSCAD enclosure)

Controls

• BtnB (middle): toggle config mode (edit target temperature)
• BtnA (up): increase target (+0.5°C) while in config mode
• BtnC (down): decrease target (-0.5°C) while in config mode
• BtnEXT: immediate power-off (shows the “sleeping kitty” screen first)

Behavior

• In normal mode, the device shows battery percent, current temperature and the alarm setpoint.
• If the measured temperature is ≥ target, it plays a short tune and sleeps briefly, then continues checking.
• Power saving:
  • Sleeps for ~60s between measurements (configurable in the sketch).
  • Auto powers off if the temperature is stable and below ~40°C for ~10 minutes, or if no probe is detected for a few minutes.

Build & Flash (Arduino IDE)

1. Install board support for M5Stack / ESP32 (as required by CoreInk).
2. Install libraries:
   • M5Unified
   • M5Unit-KMeterISO
3. Open ThermoTimer.ino, select the CoreInk board + serial port, and upload.

Project Layout

• ThermoTimer.ino: firmware
• M5ThermoTimer_case.scad: 3D-printable enclosure (OpenSCAD)
• kitten_200x200_1bit.*: monochrome bitmap used for the sleep/off screen

License

MIT (see LICENSE).