Milfra Smart Dimmer Switch

Overall description

Milfra dimmers are another type of in-wall, brightness-only light dimming devices with Tuya-Smart application support, and support 3+ way installations.

Technical details

The device is using Tuya-compatible application structure with two main components:

• application-specific MCU, responsible for controlling light output, and
• a Tuya CBU module that contains application level logic.
  • external switch input GPIO is connected to secondary MCU,
  • communication to dimming MCU is bidirectional, currently haven't determined what data the MCU is requesting from Tuya that causes an unknown command 0x34 error

Programming

First programming was done over USB-serial. The module needs disassembled (pretty easy) and moderate soldering skills are required to attach USB-RS232 converter cables. Did not test if CloudCutter or other methods would work.

Need to solder cables Rx, Tx, Gnd, Vcc (3V3) and CEN pin. Preferred flashing software is ltchiptool from LibreTiny project. Start programming like:

ltchiptool flash write <firmware.uf2>

then short CEN pin to ground for a moment to initiate progrmming mode on the module.

GPIO Pinout

Pin	Function
GPIO10	UART RX
GPIO11	UART TX

Basic configuration

substitutions:
  device_name: dimmer1
  icon: "mdi:light-switch"
  update_interval_wifi: "60s"

esphome:
  name: ${device_name}
  friendly_name: dimmer1

bk72xx:
  board: cbu

# Enable logging
logger:

# Enable Home Assistant API
api:
  encryption:
    key: CHANGEME

ota:
  password: CHANGEME

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "dimmer1"
    password: !secret wifi_password
  use_address: xxx.xxx.xxx.xxx

captive_portal:

sensor:
  - platform: uptime
    name: Uptime

uart:
  rx_pin: GPIO10
  tx_pin: GPIO11
  baud_rate: 115200

tuya:

light:
  - platform: tuya
    name: dimmer
    dimmer_datapoint: 2
    min_value_datapoint: 3
    switch_datapoint: 1
    min_value: 200
    max_value: 1000

select:
  - platform: tuya
    enum_datapoint: 13
    name: Work Mode
    optimistic: true
    options:
      0: Light_White
  - platform: tuya
    enum_datapoint: 14
    name: Relay Status
    optimistic: true
    options:
      0: "Off"
      1: "On"
      2: Memory

text_sensor:
  - platform: wifi_info
    ip_address:
      name: "IP"
      icon: "mdi:ip-outline"
      update_interval: ${update_interval_wifi}
    ssid:
      name: "SSID"
      icon: "mdi:wifi-settings"
      update_interval: ${update_interval_wifi}
    bssid:
      name: "BSSID"
      icon: "mdi:wifi-settings"
      update_interval: ${update_interval_wifi}
    mac_address:
      name: "MAC"
      icon: "mdi:network-outline"
    scan_results:
      name: "Wifi Scan"
      icon: "mdi:wifi-refresh"
      update_interval: ${update_interval_wifi}
      disabled_by_default: true
  - platform: libretiny
    version:
      name: LibreTiny Version