E-ink CO2 Monitor

A battery-powered ESPHome device that displays air quality data and temperature on a 2.13" e-ink screen.

Features

• Air Quality Monitoring: Displays CO2 levels in ppm with temperature and humidity readings
• Ultra Low Power: Uses deep sleep mode with 30-minute update intervals to maximize battery life
• Smart Sleep Schedule: Automatically sleeps from 8 PM to 5 AM to conserve power during off-hours
• Battery Monitoring: Shows current battery voltage and percentage with low battery warning display
• Wireless Updates: Over-the-air (OTA) firmware updates via Home Assistant
• Always-On Display: E-ink technology provides continuous visibility without power consumption

Hardware

• Microcontroller: ESP32 Feather board
• Display: Waveshare 2.13" e-ink display (TTGO-B74 model)
• Power: Battery-powered with voltage monitoring on pin 35
• Connectivity: Wi-Fi for Home Assistant integration
• E-Ink + Controller: https://www.aliexpress.us/item/3256802876849280.html
• Case: https://www.printables.com/model/412141-lilygo-ttgo-t5-213-case

Home Assistant Integration

Retrieves sensor data from Home Assistant entities:

• Office CO2 levels from weather station
• Temperature and humidity readings
• Publishes battery status back to Home Assistant

Display Layout

Normal Mode:

• Large CO2 reading in ppm
• Temperature and humidity in top-right corner
• Vertical accent bar on the left

Low Battery Mode:

• Battery icon warning when voltage drops below 3.5V

Power Management

• Sleep Duration: 30 minutes between updates
• Active Time: 10 seconds per wake cycle
• Night Mode: Deep sleep from 8 PM to 5 AM
• Battery Life: Optimized for weeks/months of operation on single charge

Configuration

The device integrates seamlessly with Home Assistant and requires minimal configuration. All sensitive credentials are stored in a separate secrets file for security.

Feel free to checkout my other little projects:

• https://github.com/TilmanGriesel/ha_trmnl_weather_station - TRMNL E-Ink Home Assistant Weather Station
• https://github.com/TilmanGriesel/graphite - A Calm and Clean Theme for Home Assistant
• https://github.com/TilmanGriesel/chipper - Small AI interface for tinkerers (Ollama, RAG, Python)