Flashing Beken BK7231N and BK7231T Chips with CH341T and PL2303 UART Adapters: A User's Experience

Hello. I'm new to the scene and trying to flash Beken devices following tutorial videos without success. I tried multiple options with no avail, and would like to get some advice.

Chips I'm trying to flash: BK7231N (Tuya USB Smart Adapter) and BK7231T (Tuya S06 IR Remote)



USB UART adapter I've tried: CH341T and PL2303


Power supply: Either directly from CH341T UART adapter or independent AMS1117 module set to 3.3v

I checked all solder joints with multimeter and made sure that the connection is secure and RX/TX of UART adapter is connected to TX/RX of BK7231 chips.

When GUI Flash Tool asks me to reset the device by either power cycling it or shorting CEN to GND, I do as instructed and I can see that the device is reset by power led turning off and on. However the tool doesn't detect it and keeps displaying 'Getting Bus' indefinitely even though I reset the device multiple times. I tried different baud rates which didn't work. I tried ltchiptool which failed to connect, too. What could be the problem here?

Does the same happen if you try to use bkWriter 1.60 for BK7231T flash?

Have you tried swapping RX and TX?

Do you keep the cables short?

How your setup looks like?

Yes, I tried bkwriter with BK7231T chip, which just counted up to 15 seconds and then displayed 'Failed'.

I tried swapping TX and RX which didn't help.

I think my cables are as short as possible, being less than 20 centimeters from solder pads to UART adapter.



My setup roughly looks like this.

Maybe something is connected to RX or TX of BK? Check your board. Maybe they use this pin for a button, or for a LED or something?

While there is a reset button and multiple LEDs on the board, I'm not sure if the TX and RX pads are connected to something else than the module.

However, my PCB is at least externally the same as the one described in this thread with the only difference being the date stenciled on my board is slightly later - May 2023 instead of December 2022 - and the BK7231 module of my device is WB3S instead of CB3S. Since that device did not require desoldering of the module, I don't think other parts on the board are the cause.

In the case of the USB adapter, the board is exactly the same as this one, including the letters.

Any chance you solved this issue I'm having exactly the same problem

Pleace provide a high quality photo of the PCB. I think that RX or TX may be used for some other purpose on this board.

We have already experienced similiar issue - the Smart Switch in this video was not flashable because of the capacitor on the board, so we had to remove this capacitor before flashing:

Watch the full video. That proves that if there is something on RX/TX, flashing may fail...

Thanks for looking into this. Here is my pcb.

Well, I must admit, I don't see much on this PCB. I am unable to tell at the moment whether RX/TX are connected somewhere futher.

Do you have a multimeter, can you investigate?

Or maybe are you able to desolder that CB3S module? I can give you some hints how to do that.

Or maybe you are indeed making some kind of beginner mistake when it comes to flashing... idk, maybe the capacitor on the board is too large to do power off/on cycle and needs to be removed?

Thanks @p.kaczmarek2 I appreciate you looking at this. Let me try to answer some of your questions, provide a little more detail and higher resolution images.

Looking closely at the PCB I don't believe TX/RX go past the solder points and thus not are connected to anything else:



I do have a multimeter and if I know what I am checking I could probably identify it, but have lack of knowledge to know what I should check myself, other than ... are grounds connected, what's the voltage on 3v3, etc.

Desoldering a full module, is probably a little above my skill level, although I saw another person replaced the beken with an esp and thought that was interesting.

I definitely could be making a newbie mistake.
I'm happy to describe or answer any questions you think would be helpful.
1. The UART/USB is identified on my pc using device manager, then I use that port in either flashing tool.
I have tried baud rates of 115200 and 921600.
2. I am using a ESP8266 as pass through UART, tried doing the same with ESP32 dev board. This appears to be a well documented approach without a separate USB/UART module.
(wiring up as follows):
- ESP EN/RST pin set to GND (to keep the on board esp off)
- ESP TX -> S06 RX (Tried it swapped)
- ESP RX -> S06 TX (Tried it swapped)
- ESP 3V3 -> S06 3V3
- ESP GND -> S06 GND

>>21015125

Unfortunately, no. I had to give up and move on to Zigbee devices. While options are more limited it's more hassle-free and works well. Maybe I'll try some other devices later but for now I'm settling with Zigbee.

I managed to get the flashing tool to recognize the device finally and it appears that I'm getting OpenBK to flash. For anyone who is running into this issue I solved it with these three tips,
1. Try swapping tx/rx
2. Make sure you have a separate 3.3v power supply.
3. When doing GND to RST repeat every couple of seconds until one of them triggers at the right time.

NEW ISSUE: The Access Point isn't appearing after flashing.

Whenever the AP dies for me, and safe mode definitely doesn't bring it up, I blast a sequence of - erase all, restore rf partition, flash original factory firmware. Check RF works again by pairing with Tuya app. Start again to free from cloud with OBK.

I think some combination, maybe twice over with reboots in between, has always worked eventually to revive it.

What does the TX2 log output say?
I flashed hundreds of devices and haven't managed to get "no access point" issue so far...

>>21025290

So.... I think my original firmware got overwritten by a second flash in the backups folder. Is that something I can find?

Also, is there any way to have logs sent to TX2 as I don't have a second UART.

mrt724 wrote:

So.... I think my original firmware got overwritten by a second flash in the backups folder. Is that something I can find?

To the best of my knowledge it is not possible to overwrite the firmware backup file taken by BK7231 easy UART flasher. This is because each created backup file has a current date/time string in the name and backup procedure takes so time so there is no chance that a backup file will be overwritten. Are you really sure that your backup file is not present? Use "open backups dir" button and check the files:

mrt724 wrote:

Also, is there any way to have logs sent to TX2 as I don't have a second UART.

Logs are always by default sent via TX2 (UART 2 TX port). The UART 1 port (TX1/RX1) is used for flashing. You don't need two separate USB to UART converters for that, you can just temorary disconnect your wire from TX1 and connect it to TX2 in order to check the debug log output.
Alternatively, after flashing OpenBeken, you can configure it to use TX1 as debug log output. See our autoexec examples for more details:
https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/autoexecExamples.md
Search for "logport" command in the samples above.