DimmerLink — Berry I2C driver for TRIAC AC dimmer control (zero-flicker, no libraries)

[robotdyn-dimmer]

Hi.
I've been working on a Berry driver for controlling AC TRIAC dimmers via I2C on Tasmota. The problem it solves: TRIAC phase-cut dimming requires precise zero-cross detection and sub-millisecond firing timing. Doing this on the ESP32 alongside WiFi/MQTT/web server tasks leads to timing conflicts, interrupt collisions, and visible flicker — especially under load.

DimmerLink offloads all time-critical operations to a dedicated MCU on the dimmer module. The ESP32 just sends simple I2C commands (set brightness 75%), and the MCU handles zero-cross detection, phase angle calculation, and TRIAC firing with microsecond precision. No dimmer libraries needed on the ESP32 side.

What the Berry driver provides

• Web dashboard sliders — one per channel, updates brightness on release
• Tasmota commands — DimmerLink_Kitchen 75, DimmerLink_KitchenCurve 2, DimmerLink_KitchenFade 10
• MQTT telemetry — brightness level, AC frequency, power state, temperature (published to tele/topic/SENSOR)
• HTTP API — http://device-ip/cm?cmnd=DimmerLink_Kitchen%2075
• Preset scenes — DimmerLinkPreset night applies named brightness levels to all devices
• Multi-device — up to 4 modules on same I2C bus, each with up to 4 channels
• Three dimming curves — Linear, RMS (incandescent), Logarithmic (LED) — switchable at runtime
• Auto-detection — on first boot, scans I2C bus and generates dimmerlink.json config

Hardware

Works with RBDimmer modules that have the DimmerLink controller built in (1CH, 2CH, 4CH variants). Standard I2C wiring: SDA, SCL, GND, VCC + 4.7kΩ pull-ups. Default address 0x50, changeable via Berry console for multi-device setups.

Installation

1. Configure I2C pins in Tasmota (Configuration → Configure Module)
2. Upload DimmerLink.be + dimmerlink_loader.be via Manage File System
3. Add load('dimmerlink_loader.be') to autoexec.be
4. Restart — sliders appear on main page

Quick example

# In Berry console or any .be script
var dim = global._dimmerlink[0]
dim.set_level(0, 75)     # channel 0, 75%

Links

• Driver files: DimmerLink.be + dimmerlink_loader.be
• Full documentation: Getting Started · Configuration · Control Methods · Code Examples
• Repository: github.com/robotdyn-dimmer/DimmerLink

Requirements

• ESP32 with tasmota32 or tasmota32-berry firmware
• Berry support (included in standard ESP32 builds)
• DimmerLink-compatible dimmer module

Note on ESP8266: Berry is ESP32-only. We're working on a native Tasmota driver (C-based) that will support ESP8266 as well. Should be available in the coming weeks.

Looking for feedback

This is the first public release. I'd really appreciate any testing feedback — especially around:

• Multi-device setups (2+ modules on same bus)
• Different load types (LED dimmable bulbs, incandescent, halogen)
• Home Assistant integration experience
• Any issues with specific ESP32 boards or Tasmota versions

If you run into problems, please open an issue on GitHub or reply here. Community input helps a lot — both bug reports and suggestions for what to add next.