Denky D4

The Denky D4 is a purpose-built open-source board designed to read Teleinfo (TIC) data from French energy meters, including the widely deployed Linky smart meter. Built around the ESP32-PICO-V3-02 system-in-package with 8MB flash and 2MB PSRAM, it provides a plug-and-play solution for integrating energy consumption data into home automation systems like Home Assistant, Domoticz, or Jeedom. The board ships pre-flashed with Tasmota firmware and supports autoconf profiles for zero-configuration setup.

The Teleinfo interface reads serial data from the meter's TIC (Teleinfo Client) output, supporting both the legacy Historique mode and the newer Standard mode used by Linky meters. An adjustable trimmer potentiometer allows fine-tuning the TIC signal sensitivity, while a dedicated blue LED provides visual feedback of incoming Teleinfo data. The board also features an SK6805-1515 addressable RGB LED for status indication and a QWIIC/STEMMA QT connector for adding I2C sensors or displays without soldering.

Designed by French maker Charles Hallard (hallard), the Denky D4 is fully open-source with schematics and PCB layout files available on GitHub. The compact single-sided design requires no assembly or soldering. Besides Tasmota, the board is also compatible with ESPHome, Arduino, and ESP-IDF, giving users flexibility in choosing their preferred firmware platform. A 3D-printable enclosure design is also available for a clean installation next to the energy meter.