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Identifying Chip for Flashing Smart Wifi Switch: Assistance Needed

Advian1 3870 26
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How can I identify the chip in this smart Wi‑Fi switch and find the UART points needed to flash it?

The switch appears to use a T34 module, which is supported by OpenBK7231T, so the main task is finding the UART pads for RX/TX before flashing [#20967246] The chip’s dot mark shows pin 1, and even if RX/TX are not routed to obvious headers you can still solder to the tiny pads directly with flux, a thin iron tip, Pb solder, and solder wick [#20967294] [#20967343] If you want the power point, VBAT/3.3V is the 3.3 V supply pad [#20982192] If soldering is too risky, try CloudCutter first, since it may work without touching the chip [#20967343] Later users also reported the device can be flashed at 115200 baud once the RX/TX wiring is correct [#21128174]
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  • #1 20967193
    Advian1
    Level 7  
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    Hi, I'm new in here and new in smart home scene.
    I bought this "Smart Wifi Switch"
    But I'm not sure what chip it has.
    Close-up of a circuit board from a smart Wi-Fi switch with various electronic components. PCB of a smart Wi-Fi switch with electronic components. Close-up view of a green printed circuit board from a Wi-Fi smart switch. Top view of a smart Wi-Fi switch label. Box of Wi-Fi smart switch with logos for compatibility with Amazon Alexa, Google Assistant, and TMALL Genie.

    can anyone please help me with this?
    Is this supported?
    I can find anything similar in the openbekeniot page.
    Not sure how to proceed about flashing this.

    Any help or link to any documentation/article will be helpful.

    Thanks.
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    #2 20967246
    p.kaczmarek2
    Moderator Smart Home  
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    Hello, have you checked our OBK page?
    https://github.com/openshwprojects/OpenBK7231T_App
    It lists T34 as supported:
    Screenshot of the OpenBK7231T/OpenBeken project introduction documentation.
    Still, in order to flash you need to locate RX and TX... hmm...
    T34 docs:
    https://developer.tuya.com/en/docs/iot/t34-module-datasheet?id=Ka0l4h5zvg6j8
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  • #3 20967268
    Advian1
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    Thanks for the quick reply. :)

    p.kaczmarek2 wrote:
    Still, in order to flash you need to locate RX and TX... hmm...

    yes, the problem is identifying the RX and TX.
    It seems 25 and 26 are RX and TX
    But how will I find that in the board? any idea?
    it's so tiny I can't even see the legs clearly with my eyes!
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    #4 20967294
    p.kaczmarek2
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    The dot mark on the chip indicates where first pin is:
    Close-up of a PCB featuring a T34 chip and a connection diagram.
    Are those UART signals routed out somewhere?
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  • #5 20967307
    Advian1
    Level 7  
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    p.kaczmarek2 wrote:
    The dot mark on the chip indicates where first pin is:
    Close-up of a PCB featuring a T34 chip and a connection diagram.
    Are those UART signals routed out somewhere?



    Close-up of a green printed circuit board with various electronic components.

    Doesn't look like they are connected to anything. 😭

    nothing on the other side either.
    Green printed circuit board with various connections and traces.

    Added after 10 [minutes]:

    will check if it is vulnerable to cloudcutter.
    if not, I'm out of luck I guess?
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    #6 20967343
    p.kaczmarek2
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    I don't think it's actually that bad. What kind of soldering iron you have? Do you have a flux? I think it should be still relatively easily to solder to those points, given the assumption that you just have some flux and a thin soldering iron tip. First I would add some flux, then I would add Pb solder. I would remove the excess solder from the pads with the soldering wick. Then, tin a tiny wire and try to solder it, soldering iron in one hand, wire in the second hand... I can try to do something like that on a video someday in a form of tutorial for our YT channel: https://www.youtube.com/@elektrodacom

    Still, check Cutter as well. I can help you with OpenBeken config once you flash it.
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  • #7 20967377
    Advian1
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    p.kaczmarek2 wrote:
    I don't think it's actually that bad. What kind of soldering iron do you have? Do you have flux? I think it should still be relatively easy to solder to those points, given the assumption that you just have some flux and a thin soldering iron tip. First, I would add some flux, then I would add Pb solder. I would remove the excess solder from the pads with the soldering wick. Then, tin a tiny wire and try to solder it, soldering iron in one hand, wire in the second hand... I can try to do something like that on a video someday in a form of tutorial for our YT channel: https://www.youtube.com/@elektrodacom

    Still, check Cutter as well. I can help you with OpenBeken config once you flash it.


    Not sure if you can see how small those are.

    here is the chip against the iron tip.
    Electronic circuit with capacitors and soldered copper wire.

    I have never worked on such a small circuit,
    so a bit afraid I'll ruin it.

    I'll try the cloud cutter first, if it doesn't work, then I'll try to solder a single strand of a copper wire and see if I can succeed.
    because I won't use it with it connected to the Chinese server anyway.

    So either it'll work, or it won't. :D

    Thanks a lot for your guidance so far. 😊😊😊

    Will certainly update you.
  • #8 20967407
    p.kaczmarek2
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    I know how small they are, I've already did soldering to QFN pad here:
    How to access hardware SPI port on CB2S? P16 (MOSI) GPIO breakout method
    If we were from the same country, I could do the job for you, but still, it's just a single switch.... and there is still a chance that WiFi method may work as well. Who knows.
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  • #9 20967424
    Advian1
    Level 7  
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    p.kaczmarek2 wrote:
    If we were from the same country, I could do the job for you

    Really appreciate the gesture! you are a kind person.

    p.kaczmarek2 wrote:
    I know how small they are, I've already did soldering to QFN pad here:
    How to access hardware SPI port on CB2S? P16 (MOSI) GPIO breakout method


    wow! I don't think I'm as good as you in soldering. I'll definitely give it a try if the wifi method fails.

    Can't thank you enough! Literally!!! it says I can't thank more than 3 post :D
  • #12 20982165
    Advian1
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    @p.kaczmarek2

    Can you please help me a bit more?
    Which one is VCC?
    Photo of a circuit board with markings indicating potential VCC connection points.
  • #13 20982192
    p.kaczmarek2
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    VBAT/3.3V is here:
    Image of an electronic module with labeled pins ANT, GND, and 3.3V and a T34 pin schematic.

    Added after 22 [minutes]:

    EDIT: I think the 3.3V is also where you marked:
    Table with information on RF PA power supply, recommending 3.3 V voltage.
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  • #14 20989234
    Advian1
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    flashed it successfully.
    Screenshot of the BK7231 Easy UART Flasher application with Write success! message.
    But after that it isn't booting.
    This is the log I'm getting over console. (attached)

    what did I do wrong?
    Attachments:
    • kitty.zip (3.47 KB) You must be logged in to download this attachment.
  • #15 20989245
    p.kaczmarek2
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    How did you get so badly corrupted log? Check the PCB for shorts.
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  • #16 20989458
    Advian1
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    p.kaczmarek2 wrote:
    How did you get so badly corrupted log? Check the PCB for shorts.

    did some cleanup, now it looks like this:
    Close-up of a circuit board with various electronic components.

    but 26 is short with ground :(
    is it dead? 😭
  • #17 20989460
    p.kaczmarek2
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    I don't think so, just clean the soldering iron tip, add some flux, and clean the excess solder with the soldering wick.
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  • #18 20989470
    Advian1
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    p.kaczmarek2 wrote:
    I don't think so, just clean the soldering iron tip, add some flux, and clean the excess solder with the soldering wick.


    That was the pic after I cleaned it. will try to clean even more.
    I'm not good at such tiny scale :(

    By the way, getting this console log on pin 28 (UART2) at the moment.
    nothing on pin 26 for now.
    Attachments:
    • kitty.zip (467 Bytes) You must be logged in to download this attachment.
  • #19 20989584
    p.kaczmarek2
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    This means that OBK firmware boots but something is wrong later. Maybe you've removed some capacitors or device does not get enough power to start.
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  • #20 20989893
    Advian1
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    p.kaczmarek2 wrote:
    This means that OBK firmware boots but something is wrong later. Maybe you've removed some capacitors or the device does not get enough power to start.

    Close-up of a circuit board with various electronic components, including capacitors and a relay.
    I don't think I can clean it any better.
    Now there is no short between pins.
    I don't see any missing or misplaced capacitor anywhere either.

    Now there is no output on the console on pin 26 at all.
    The flasher app doesn't detect it either.
    Stuck at "Getting bus..."

    Pin 28 has the same output on the console as earlier.

    I provided power with an am1117 this time.
    So power shouldn't be an issue.

    Not sure what else to try.
  • #21 20996942
    seeindarkness
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    Here is the pinout for the device:
    P6 - Wifi_led
    P14 - Get
    P15 - Relay
    P24 - Btn

    Easier connection points for flashing
    Close-up view of a circuit board with pin labels.
  • #22 20996944
    Advian1
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    seeindarkness wrote:
    Here is the pinout for the device:
    P6 - Wifi_led
    P14 - Get
    P15 - Relay
    P24 - Btn


    Thanks for replying.
    But the current problem is, I haven't been able to boot it up after flashing.
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  • #23 21090302
    kkarmah
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    Good morning everybody.
    Did you manage to flash it without desoldering the chip?
    I'm trying to do it but in "BK7231 Easy UART Flasher" it always gives me the error "Failed to set baud rate!"
    Whether I choose 921600 or 115200...

    The connections I have are these (without unsoldering):
    GND - GND
    RX - TX
    TX - RX
    VBAT - 3.3V

    And to start the flash attempt, I disconnect the VBAT pin and connect it again to TTL.
    I'm not using the CEN pin.


    Screenshot of BK7231 Easy UART Flasher with baud rate setting error.

    Thank you all
  • #24 21090876
    p.kaczmarek2
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    Have you tried lower baud setting?
    Is anything connected to RX/TX on the board?
    How do you power the circuit? The large bulk capacitor on the board may interfere and/or overload the power supply...
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  • #25 21091187
    kkarmah
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    Thank you friend.
    Because you asked about the RX and TX, I went to check if they were touching each other and they were! As it is so difficult to solder to the right pin, they seemed to be far from each other but they weren't...
    I've already managed to flash it, now I'm configuring it but I have a question. What is the pin "P14 - GET"? I don't have any on the list.

    Screenshot of a pin configuration interface.

    Another question, on the main page I see "boot incompletes 1". What does this mean? Should I be worried?
    Screenshot of a software interface displaying device status information.

    Thanks
  • #26 21128174
    nebuknadezur
    Level 1  
    Posts: 1
    Soldering the RX / TX wire was a bit tricky, but it works without any problems. I set the baud rate to 115200, the flashing worked wonderfully.
    Interesting, after klick on the starting the flash button it is requested to disconnect the VCC, then the flash process started and flashed everything until end WITHOUT necessary reconnecting the VCC.

    By the way, in the configuration, I didn't find "P14 - GET" either, don't know what that is. I left the P14 unconfigured, the switch works just fine.
    Sorry for the blurry photo…

    Thanks for the support !
    Close-up of a circuit board with soldered copper wires and electronic components. Blurry image of a circuit board with wires connected to a programmer attached to a USB port.
  • #27 21128187
    p.kaczmarek2
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    I don't know what this user means by "GET", maybe LED? A typo? Still, if unsure, you can do Tuya config extraction:


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Topic summary

✨ A user seeks assistance in identifying the chip in their Smart Wifi Switch for flashing purposes. They reference the OpenBeken project and inquire about locating RX and TX pins for flashing. Responses suggest checking the OBK page for supported modules, specifically the T34, and provide guidance on soldering techniques for small components. The user struggles with identifying the correct pins and expresses concern about damaging the circuit. After several attempts, they successfully flash the device but encounter boot issues, leading to further troubleshooting discussions about potential shorts and power supply problems. Ultimately, they manage to flash the device and configure it, although some pin functions remain unclear.
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FAQ

TL;DR: For anyone flashing a tiny Smart WiFi Switch, the thread identifies a supported Tuya T34/BK7231 module, points to UART on pins 25 and 26, and confirms 3.3V power; as one expert put it, "The dot mark on the chip indicates where first pin is." [#20967294]

Why it matters: This FAQ gives a practical path from chip identification to safer flashing when pads are extremely small.

Method Best use in this thread Main advantage Main limitation
Cloudcutter First try when pads are too small No soldering if supported May not work on this switch
UART flashing When direct access is possible Confirmed successful by multiple users Requires soldering to tiny pads

Key insight: The breakthrough was not chip support but physical access: once users identified pin 1, traced UART, and avoided RX/TX shorts, flashing at 115200 baud worked on this switch. [#21128174]

Quick Facts

  • The switch was identified as using a Tuya T34 module, and the OpenBeken page linked in the thread listed T34 as supported. [#20967246]
  • The thread repeatedly maps UART to pins 25 and 26, with later console output also observed on pin 28 during troubleshooting. [#20967268]
  • Power for flashing was taken from VBAT/3.3V, and the helper later confirmed the marked pad was also 3.3V. [#20982192]
  • Two baud rates were tested in BK7231 Easy UART Flasher: 921600 and 115200; users later reported reliable flashing at 115200 baud. [#21128174]
  • A reported working OpenBeken pin map for this device was P6 = WiFi LED, P15 = Relay, and P24 = Button; P14 = GET remained unclear and was left unconfigured by one user. [#21128174]

How can I identify whether a Smart WiFi Switch uses a Tuya T34/BK7231 chip and check if it is supported by OpenBeken?

Check the module marking first, then compare it with the OpenBeken support list. In this thread, the helper pointed to the OpenBeken page and stated that T34 is supported, then linked the Tuya T34 datasheet for pin reference. That is the fastest confirmation path when the retail product name says only “Smart WiFi Switch.” [#20967246]

Where are the RX and TX pins on a Tuya T34 module, and how do I trace them on a tiny smart switch PCB?

In this thread, RX and TX were identified as pins 25 and 26 on the Tuya T34. To trace them on a tiny PCB, first locate pin 1 from the chip dot, then count pins around the package and check whether those pads route to exposed test points; on this board, they did not appear to route anywhere obvious. [#20967307]

What is the pin 1 dot marking on a QFN chip, and how do I use it to find UART pins like RX and TX?

The pin 1 dot is the orientation mark that shows where numbering starts on the QFN package. The helper explicitly said, “The dot mark on the chip indicates where first pin is,” which lets you count forward to locate UART pins such as 25 and 26 on the T34. [#20967294]

How do you solder wires to very small QFN pads for flashing a BK7231/T34 smart switch without lifting pads or shorting pins?

Use a controlled, low-force process. 1. Add flux to the tiny pads. 2. Add a small amount of Pb solder, then remove excess with solder wick. 3. Pre-tin a very thin wire and tack it to the pad with a fine tip. The helper described exactly that sequence for these tiny pads and suggested it was still practical on this switch. [#20967343]

What tools and materials work best for soldering onto tiny Tuya module pads, such as flux, solder wick, thin wire, and fine-tip irons?

The thread recommends flux, Pb solder, solder wick, a thin wire, and a soldering iron with a thin tip. Those materials matter because the pads are QFN-scale and easy to bridge. The helper’s advice was to flux first, tin sparingly, wick away extra solder, and then attach a pre-tinned small wire. [#20967343]

Cloudcutter vs UART flashing for Tuya smart switches: which method is better when OpenBeken flashing pads are hard to access?

Try Cloudcutter first when the pads are too small, then fall back to UART if Wi-Fi flashing fails. "Cloudcutter" is a software flashing method that targets compatible Tuya devices over Wi-Fi, avoiding direct soldering, but its key characteristic is that support varies by device and firmware. In this thread, the user chose Cloudcutter first specifically because the UART pads were tiny and difficult to reach. [#20967377]

How can I find the 3.3V or VBAT pin on a Tuya T34-based smart switch before connecting a USB-to-TTL adapter?

Use the board photos and the module pin reference to locate the VBAT/3.3V pad before wiring the adapter. The helper marked one point as VBAT/3.3V and then added that the user’s highlighted pad also looked like 3.3V, which gave a safe power point for the TTL connection. [#20982192]

Why does BK7231 Easy UART Flasher show 'Failed to set baud rate!' when flashing a T34 smart switch, and how can I fix it?

A short or bad solder joint on RX/TX can cause that error. In the thread, a later user saw “Failed to set baud rate!” at both 921600 and 115200, then discovered RX and TX were accidentally touching; after separating them, flashing succeeded. Also check whether anything else is loading RX/TX and whether the power source can handle the board capacitor. [#21091187]

What does a corrupted or garbled UART console log after flashing OpenBeken usually mean on a BK7231/T34 device?

It usually means the board has a hardware problem after flashing, not necessarily dead firmware. The helper’s first response to the badly corrupted log was to check the PCB for shorts, and later added that if OpenBeken boots but fails later, missing parts or weak power can also stop normal startup. [#20989584]

Why would pin 26 appear shorted to ground after soldering, and how do I safely remove excess solder from a tiny smart switch board?

Pin 26 can appear shorted to ground because excess solder has bridged adjacent pads. The safe fix is simple: clean the iron tip, add flux, and use solder wick to remove the extra solder. That was the direct repair advice given after the user reported pin 26 shorted to ground. [#20989460]

What does 'boot incompletes 1' mean in OpenBeken, and when should I worry about it after flashing a smart switch?

The thread does not define it, so you should only worry if it appears together with failed startup symptoms. In this case, the more serious signs were no normal boot after flashing, no detection by the flasher, and UART activity only on pin 28. The unanswered “boot incompletes 1” question means the thread offers no confirmed fault meaning by itself. [#21091187]

What is 'P14 - GET' in a Tuya/OpenBeken pinout, and what function should be assigned if that label does not exist in the configuration list?

Do not assign it blindly; leave it unconfigured unless you verify it. One user reported the pin map as P6 WiFi LED, P14 GET, P15 Relay, P24 Button, but another later said they could not find “GET” in the configuration list and left P14 unset while the switch still worked normally. [#21128174]

How do I configure OpenBeken for this Smart WiFi Switch using the reported pins P6 WiFi LED, P15 Relay, and P24 Button?

Set P6 as the WiFi LED, P15 as the relay output, and P24 as the button input. That exact mapping was posted later in the thread as the device pinout. If you cannot verify P14 GET, you can leave it unconfigured first and test basic switching, because another user reported the switch worked fine without assigning P14. [#20996942]

What is Tuya config extraction, and how can it help when a device pin description like 'GET' seems unclear or mislabeled?

It is a way to pull the device’s original Tuya configuration so you can verify uncertain labels. "Tuya config extraction" is a recovery and analysis method that reads a device’s stored Tuya setup, preserving original pin-role data, and its key characteristic is that it helps resolve unclear names such as “GET” without guessing. The helper recommended it specifically when “GET” looked like a typo or unclear label. [#21128187]

Which baud rate and power-up sequence are most reliable for flashing a T34/BK7231 smart switch with BK7231 Easy UART Flasher?

In this thread, 115200 baud was the most clearly confirmed working setting. One successful user said flashing worked “wonderfully” at 115200, and noted an unusual sequence: after pressing start, the tool asked for VCC disconnect, then the flash continued to the end without reconnecting VCC. That makes 115200 the safest first setting here. [#21128174]
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