Tuya Dimmer BK7231N Serial Protocol: Hex Commands for On/Off & Backlight Control

I have a Tuya dimmer switch, It has a Beken unit in it BK7231N it had a and and - symbol on it and a middle on and off switch.
It talks serial to a chip that is unmarked with a baud rate of 9600



The protocol is structured so a variable length of hex values is sent and then some are received. The ones that are received contain the status. The sending ones are telling the electronics what to do (Control). All message start with 55 this gives a nice square wave for each side to sync with. Then AA...

Here are the signals I found that do specific thinks like

on/off .
This is the protocol in hex values.
TX
light on
55AA0006000501010001010E

RX
55AA03070005010100010112
55AA03070005010100010112
55AA03070008020200040000030C28
55AA03070008030200040000000A24
55AA0307000805020004000003E807
55AA0307000806020004000000001D
55AA030700050E040001002155AA030700051A010001012B

light off
TX
55AA0006000501010001000D

RX
55AA03070005010100010011
55AA03070005010100010011
55AA0307000802020004000000D0E9
55AA03070008030200040000000A24
55AA0307000805020004000003E807
55AA0307000806020004000000001D
55AA030700050E040001002155AA030700051A010001012B

by holding down the middle button the back light can be turned on and off. With the following signals.

back light on
TX
55 AA 00 06 00 05 1A 01 00 01 01 27

RX
55AA030700051A010001012B
55AA03070005010100010011
55AA0307000802020004000000637C
55AA03070008030200040000000A24
55AA0307000805020004000003E807
55AA0307000806020004000000001D
55AA030700050E0400010021
55AA030700051A010001012B

back light off
TX
55 AA 00 06 00 05 1A 01 00 01 00 26

RX
55AA030700051A010001002A
55AA03070005010100010011
55AA0307000802020004000000637C
55AA03070008030200040000000A24
55AA0307000805020004000003E807
55AA0307000806020004000000001D
55AA030700050E0400010021
55AA030700051A010001002A

Here is the TX when adjusting the brightness
dimmness 15 byte tx
TX Brightness
55AA00060008020200040000001429 1%
55AA00060008020200040000001E33 2%
55AA0006000802020004000000283D 3%
55AA00060008020200040000003247 4%
55AA0006000802020004000000455A 5%
55AA0006000802020004000000596E 6%
55AA0006000802020004000000778C higher I can't remember what this one was.

There is a long press on the bottom "-" button on the physical light switch that will put the beken unit into access point mode so the Tuya app can tell it what wifi details to use. I will capture this at some point.

What I need is to work out how to get openbeken to send these serial commands over the tx0 and rx0 pins.

You can use this tool to see more in depth results of those packets - https://github.com/openshwprojects/TuyaMCUAnalyzer

Thanks, that is really helpful. Do you know if I can set up a slider that sends the appropriate serial message out?

Certainly, have you found which dpID does what on your device?

Once you do, there are multiple tutorials on how to map Tuya dpID's and manipulate them, there are also several examples of that in our docs section - https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/autoexecExamples.md

There is also simulator what runs under windows so you can test your settings, not particularly suited for Tuya dpID's but you can test autoexec files and settings, home page look etc. Link for latest simulator - https://github.com/openshwprojects/OpenBK7231...s/download/1.18.225/obkSimulator_1.18.225.zip

Feel free to share a bit more and we can try and help you customize your device more.

So, the good news is I have the three controls working.

The on and off toggle.
The backlight toggle.
The dimmer slider in the GUI.

I added these commands to the startup commands.


I wired up the TX line from the device to the RX1, but when I manually adjusted the light it did not update the web GUI. Can this be done?

Why are you doing that?

You are manually sending data via UART. You're sending SetDP command:

Why not do it directly, with our TuyaMCU driver?
It will work in both directions then.
Our command is: linkTuyaMCUOutputToChannel
https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/commands.md
https://www.elektroda.com/rtvforum/find.php?q=linkTuyaMCUOutputToChannel

Here is one of my dimmer guides:
https://www.elektroda.com/rtvforum/topic3929151.html
You can see my autoexec.bat there and how I used linkTuyaMCUOutputToChannel to link TuyaMCU dpIDs to OBK channels.

It's very easy to run TuyaMCU with OBK, it's the recommended solution. You can do it also manually with OBK scripts and uartSendHex , but why?

My suggestion: remove all uartSendHex calls and use linkTuyaMCUOutputToChannel for all dpIDs.

Yep, it turns out this worked in the end



Thanks. It works bidirectionally also now.