Unknown bootloader CRC - 0x3D27F00A (Tuya - BK7231N - CB2S)

[Chriss312]

Hello everyone,

i have a unknown device a Ledvance Outdoor Plug EU with energymeter.

https://shop.ledvance.com/products/osram-matter-smart-compact-plug-smarte-outdoor-steckdose-schwarz

It is a CB2S inside with a BL0542 Powermonitor IC.
TUYA Smartlife App say it ist 2.0.4 installed.

I cannot find a firmwareprofile for this Firmware in Cloudcutter.

ltchiptool_bk72xx_2025-10-16_12-38-32.zip

Support me please.

Chriss

[Cossid]

This appears to be Bootloader BK7231N_3.0.0 which is not currently compatible with 3rd party firmware.
The bootloader and Tuya firmware are from the matter line, which will not be compatible with CloudCutter.

The recommendation for now is to serial flash the BK7231N_1.0.1 bootloader from other devices at 0x0 and then serial flash your 3rd party firmware (as it is safe to replace bootloaders on the BK7231N line).

It looks like the configuration is in plain text:

{reset_t:5,netled1_pin:8,rl1_lv:1,bt1_pin:26,chip_type:3,lose_vol:150,over_vol:275,module:CB2S,net_trig:3,ch_cddpid1:9,jv:1.0.3,netled1_lv:1,netled_reuse:1,ch1_stat:0,ch_num:1,total_stat_time:5,ele_fun_en:1,over_cur:17000,rl1_pin:6,vol_def:0,ch_dpid1:1,bt1_lv:0,crc:123,}

@kuba2k2 I'll leave it to you to add (or avoid) support for the bootloader. BK7231Tools can extract the bootloader, but not the app partition currently.

[Chriss312]

@Cossid Thank you very much for your hint to change the bootloader.

I created a dump from another ledvance product called remote control with a unknown bootloader. Because i had no idea where i get an old Bootloader with the Version 1.0.1 from . So it was a try and the result was, it works. :)

And one update to the Ledvance outdoor plug. It is not a BL0542. It is a BL0942 Energy Monitor IC. I am 40. So my eyes are not so good anymore. ;p

Here is my first try with esphome and this yaml file works. But for the community i destroyed the enclosure so i need another one to test the energy monitor.

I will update this ticket with a Howto document.
But after that i need support for:

Where should i share the knowledge about the ledvance outdoor plug eu?
Because this is a issue ticket for LTchiptool and unknown bootloader. But the root of the sucessful story.

esphome:
  name: outdoorplug

bk72xx:
  board: generic-bk7231n-qfn32-tuya

logger:

web_server:

captive_portal:

mdns:

api:
  password: ""

ota:
  platform: esphome
  password: ""

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

uart:
  id: uart_bus
  tx_pin: P11
  rx_pin: P10
  baud_rate: 4800
  stop_bits: 1

text_sensor:
  - platform: libretiny
    version:
      name: LibreTiny Version

binary_sensor:
  - platform: gpio
    id: binary_switch_1
    pin:
      number: P26
      inverted: true
      mode: INPUT_PULLUP
    on_press:
      then:
        - switch.toggle: switch_1

switch:
  - platform: gpio
    id: switch_1
    name: Relay 1
    pin: P6
    on_turn_on:
      - light.turn_on: light_status
    on_turn_off:
      - light.turn_off: light_status

light:
  - platform: status_led
    id: light_status
    pin:
      number: P8
      inverted: true

sensor:
  - platform: uptime
    name: Uptime
  - platform: bl0942
    uart_id: uart_bus
    current:
      name: BL0942 Current
    voltage:
      name: BL0942 Voltage
    power:
      name: BL0942 Power
      filters:
        multiply: -1
    energy:
      name: BL0942 Energy
    frequency:
      name: BL0942 Frequency
      accuracy_decimals: 2

Maybe an improvment for the ltchiptool.

• A dropdown menu with "old" Bootloaders for different modules like WB2S and CB2S and so on. or better.

• A merge with an "old" bootloader and the latest version of esphome kickstarter in front of this preparation page
  https://upk.libretiny.eu/?profile=tuya-generic-lspa9-plug-v1.1.8