# Denky D4

> Open-source ESP32 Teleinfo reader board for French Linky energy meters. Pre-flashed with Tasmota, features USB-C, WiFi, QWIIC I2C port, and RGB LED. Reads both Standard and Historique TIC formats.

## Quick Facts

- **Brand:** hallard
- **Board Type:** IoT Sensor Board
- **Price:** ~$26.9
- **Product Readiness:** consumer
- **CPU:** ESP32-PICO-V3-02
- **CPU Architecture:** Xtensa LX6 dual-core
- **CPU Cores:** 2
- **RAM:** 520KB SRAM
- **PSRAM:** 2MB
- **Flash:** 8MB
- **USB:** USB-C (CH9102)
- **Power:** 5V
- **Operating Voltage:** 3.3V
- **Antenna:** U.FL (footprint)

## Connectivity

- **Wifi:** 802.11 b/g/n
- **Bluetooth:** BLE 4.2

## Open Source

- **Firmware:** Yes
- **Schematics:** Yes
- **PCB Layout:** Yes

## Compatible Firmware

tasmota, esphome, arduino, esp-idf, micropython

## Use Cases

- energy-monitoring
- teleinfo-reader
- home-automation
- smart-metering
- iot
- data-logging

## Components

- **ESP32-PICO-V3-02** (mcu): ESP32 system-in-package with dual-core Xtensa LX6 processor at 240MHz, integrated 8MB flash and 2MB PSRAM, WiFi and Bluetooth 4.2 connectivity — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.espressif.com%2Fsites%2Fdefault%2Ffiles%2Fdocumentation%2Fesp32-pico-v3-02_datasheet_en.pdf&ref=openhardware.directory&product=denky-d4&source=md-export)
- **CH9102** (usb-uart): USB to serial UART bridge IC providing USB-C connectivity for programming and serial communication — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.wch-ic.com%2Fproducts%2FCH9102.html&ref=openhardware.directory&product=denky-d4&source=md-export)
- **SK6805-1515** (led-driver): Ultra-compact 1.5x1.5mm addressable RGB LED with integrated driver, WS2812-compatible protocol, used for status indication — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fcdn-shop.adafruit.com%2Fproduct-files%2F4492%2FDatasheet.pdf&ref=openhardware.directory&product=denky-d4&source=md-export)
- **Teleinfo Interface** (sensor): Optocoupler-based interface circuit for reading French energy meter TIC serial data, supports both Standard (9600 baud) and Historique (1200 baud) modes with adjustable sensitivity trimmer — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fgithub.com%2Fhallard%2FDenky-D4&ref=openhardware.directory&product=denky-d4&source=md-export)

## Protocols

- **I2C**
- **UART**
- **USB**
- **GPIO**

## GPIO Map

| Pin | Name | Type | Functions |
|-----|------|------|-----------|
| GPIO8 | Teleinfo Rx | — | — |
| GPIO14 | RGB LED (SK6805) | — | — |
| GPIO21 | I2C SDA | — | — |
| GPIO22 | I2C SCL | — | — |

## Description

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.

## Where to Buy

- [Tindie](https://openhardware.directory/r?to=https%3A%2F%2Fwww.tindie.com%2Fproducts%2Fhallard%2Fdenky-d4-esp32-tic-teleinfo-reader%2F&ref=openhardware.directory&product=denky-d4&source=md-export) — $26.90

## Resources

- [product](https://openhardware.directory/r?to=https%3A%2F%2Fwww.tindie.com%2Fproducts%2Fhallard%2Fdenky-d4-esp32-tic-teleinfo-reader%2F&ref=openhardware.directory&product=denky-d4&source=md-export)
- [github](https://openhardware.directory/r?to=https%3A%2F%2Fgithub.com%2Fhallard%2FDenky-D4&ref=openhardware.directory&product=denky-d4&source=md-export)
- [schematics](https://openhardware.directory/r?to=https%3A%2F%2Fgithub.com%2Fhallard%2FDenky-D4&ref=openhardware.directory&product=denky-d4&source=md-export)

## Tags

`esp32`, `teleinfo`, `energy-monitor`, `linky`, `tasmota`, `esphome`, `open-source`, `french-energy-meter`, `tic`, `home-automation`, `wifi`, `qwiic`, `usb-c`

## Images

![Denky D4](https://nbg1.your-objectstorage.com/openhardware-directory/entities/denky-d4/32080674a7bd.png)
![Denky D4](https://nbg1.your-objectstorage.com/openhardware-directory/entities/denky-d4/839be212563f.png)
![Denky D4](https://nbg1.your-objectstorage.com/openhardware-directory/entities/denky-d4/7a5f120f5d92.jpg)
![Denky D4](https://nbg1.your-objectstorage.com/openhardware-directory/entities/denky-d4/419b89bd253b.jpg)

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