Reading/writing errors on tuya mini switches - issues with arduinos?

Question

Hi all, I'm new to the tuya flashing world! I have two of the switches listed in this thread, but can't manage to flash them, they have firmware 1.3.10 v102. I wired them up like was shown in the first post of said thread. I get several errors during the flashing process after repeatedly...

p.kaczmarek2 · Answer

Timings may be a bit more crucial here, I'd just try using the USB to UART converter that we've used on our videos:
[youtube]https://www.youtube.com/watch?v=YQdR7r6lXRY [/youtube]
Try it out once your converter arrives and let us know if it worked better.

Have you tried flashing at lower baud rates?

donut343 · Answer

Thanks for getting back to me! Could you elaborate on timings being more crucial? I only had to connect and disconnect the PSU the first try @ 115200 baud rate, after that I could just re-click the "write only" button and it would recognize without any manual interference. I'm hoping the USB converters work out, of course I'll update this thread once I receive them, should be a week or so.

The flashing tool only listed 115200 and up, with respect to baud rates. If I understand what you mean correctly, I tried to manually type 9600 in the flashing tool. I had also flashed the Arduinos with SoftwareSerial with 9600 baud rate, but couldn't get the Tuya chip to be recognized by the flashing tool, only 115200 resulted in recognized bus. Higher baud rates I also couldn't get working with the Arduinos..

p.kaczmarek2 · Answer

I haven't investigated the timings with scope but I know that there are even issues with running my flasher (BK7231 easy uart flasher) on Mono on Linux because they have slightly different UART implementation. I also remember situations when using different USB to UART converter helped, so I am speaking from the experience.

what else can we do... well, there is one hack that worked few times for me. Do the following:
1. disconnect VDD of module from your 3.3V supply
2. temporarily connect VDD of module side to GND (not the 3.3V of your power supply! do not do short!)
3. start flashing in the flasher (so it's getting bus)
4. disconnect module VDD from GND and connect it to 3.3V

Alternatively you can also use the CEN method.... but in general, I've flashed hundreds of devices, once you get setup right, it's 100% reliable, it may not be worth trying to use complicated methods when a simple converter works just fine.

The last thing you can try (I am often doing that) is feeding 5V to the input of the LDO on the board with Beken. Do this instead of connecting 3.3V. I am sometimes using this method when there is a clearly visible AMS1117-3.3V or a step down (5V to 3.3V or so) converter on the board.

That being said, I kinda remember there were people who have successfully used NodeMCU (with MCU in RESET state) for flashing,..

Wait, to be clear - when trying to use USB to UART converter from Arduino UNO, do you put Arduino in RESET state by shorting it's RESET pin to ground?

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.

donut343 · Answer

Thanks for your advice, really appreciated. I think I will do as follows:

1. Wait for the USB-UART converters (I ordered a 3-pack containing a PL2303, CP2102, and CH340G based converter)
2. Try your suggested hack
3. Try your second suggested hack of feeding 5V to the LDO instead of 3.3V

I've tried with both an Arduino Uno and a Nano by shorting reset-gnd to bypass the MCU and then just using RX and TX pin; doing so I couldn't get the Tuya chip to be recognized by the tool. I also tried SoftwareSerial with digital pins as RX and TX pins, like shown in the code block in my first post; that method at least got the tool to start erasing sectors.
But first, I'll wait for the USB-UART converters and follow the setup in the video - I'll likely use my ATX benchtop PSU to output 3.3V instead of the USB + LDO though.

donut343 · Answer

So using a new USB-UART TTL converter did the trick, I successfully managed to flash the chip with new firmware.

However, on desoldering the wires I accidentally desoldered an SMD component and then it sprung off my PCB when I tried to resolder it and I lost it haha, pretty stupid!! Just hooked it up and it did set up an access point, I'll see if the missing component results in real noticeable errors :3

I do have 2 more chips to flash and it was only a few dollars, still a shame though lol. At least I know the flashing works! See attached image for the component I lost circled in red.. I'll update after I flash some firmware on them and test them with home assistant.

p.kaczmarek2 · Answer

Looks like a part of WiFi antenna circuit, is your WiFi range still ok?

donut343 · Answer

Hmm so the access point is showing up (full bars) but I can't connect to it with my MacBook.. With my phone I can, but then can't reach it over 193.168.4.1 - tomorrow I'll try flashing the other identical chip I have and be more careful with the near components 😅

p.kaczmarek2 · Answer

That's strange, but still, you can configure your device WiFi via our flasher itself.

donut343 · Answer

I'll resolder the wires and check it out tomorrow, unfortunately I have no more time tonight, I'll keep you posted on my progress!

p.kaczmarek2 · Answer

Still, issue is most likely caused by missing capacitor. Can you solder a replacement? Here is a schematic:

max4elektroda · Answer

Just to make sure this is a typo? IP is 192.168.4.1

p.kaczmarek2 · Answer

Nice spotting, it could have been a typo, let's wait for @donut343 to recheck...

donut343 · Answer

yes, sorry, that was a typo indeed haha. Thanks for the schematic, hope I can locally source a capacitor or I'll have to wait for a while. Would that be c9 or am I misreading the schematic you sent over? Sorry for my oblivious questions, I'm quite inexperienced with all this stuff.

donut343 · Answer

Okay so for some reason my (android) phone and macbook didn't work, but my windows desktop did, using a wifi dongle I had plugged in a rpi, I just changed wifi ssid / pass in settings and seems to connect fine, wifi signal seems okay! Now to flash the actual firmware and test

Thanks for all the time you spent on helping me, regardless! Much appreciate, I've been recommending your tool / forum to interested people around me!

p.kaczmarek2 · Answer

I see, that's a very good news. Don't forget that we're building a supported devices list here: And you can contribute:

donut343 · Answer

Yeah I will do, once I get it up and running! I think others have reported this one already ( but I'll report regardless

Reading/writing errors on tuya mini switches - issues with arduinos?

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