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[BK7231N / CB3S] Tuya Smart Dual GPO

TurkeyMan 1311 0
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  • Teardown of this smart dual GPO from AliExpress.

    [BK7231N / CB3S] Tuya Smart Dual GPO

    Product seems to be branded MEAKISS, but I can't see that written anywhere on the device, and this OEM probably sells to many brands.
    No product name/model number is written anywhere on the device.

    [BK7231N / CB3S] Tuya Smart Dual GPO
    [BK7231N / CB3S] Tuya Smart Dual GPO

    Product has 2 GPO's with 2 touch buttons. The product was advertised with energy metering, but this device does NOT have an energy meter.

    Device is extremely easy to disassemble. The front plate removes with clips:
    [BK7231N / CB3S] Tuya Smart Dual GPO

    Which reveals the wifi board on a pin-mounted riser:
    [BK7231N / CB3S] Tuya Smart Dual GPO
    [BK7231N / CB3S] Tuya Smart Dual GPO

    Behind the wifi board:
    [BK7231N / CB3S] Tuya Smart Dual GPO

    Removing the power board, we see a pair of relays:
    [BK7231N / CB3S] Tuya Smart Dual GPO
    [BK7231N / CB3S] Tuya Smart Dual GPO

    Trying to look for power metering chips as advertised, but none seem to be present:
    [BK7231N / CB3S] Tuya Smart Dual GPO

    It looks like this is where the metering chip should be located, but the board is not populated:
    [BK7231N / CB3S] Tuya Smart Dual GPO

    Flashed OpenBK with no problem using the command:
    python uartprogram ./OpenBK7231N_QIO_1.15.152.bin --unprotect -d com7 -w --startaddr 0x0

    The pinouts seem to be:
    P6 - Blue LED 1 (right)
    P7 - Button 1 (right)
    P8 - Blue LED BOTH SIDES
    P9 - Button 0 (left)
    P14 - Relay 1 (right)
    P24 - Blue LED 0 (left)
    P26 - Relay 0 (left)

    The LED's are configured in an interesting way. On each button there are 3 LED's; there is a red LED, which turns on when the socket is energised. It can not be controlled by software.
    There are also 2x blue LED's on each side. One of the LED's on each side can be controlled individually by P24 and P6, but there is a second blue LED which is controlled by P8, and it illuminates both sides at the same time.
    If P8 is enabled at the same time as P6 or P24, then the 2x blue lights become very bright.

    I'm not sure what P8 is for. I didn't see it used by the stock firmware... except maybe it was P8 that was blinking when I first turned the device on; flashing to notify me that the device needed to be configured and to run the Tuya App. After initial configuration, it stopped flashing, and it didn't seem to have any function.

    The combination of blue and red LED's allows to put the ports into a purple light state too if they are both illuminated. I'm not sure what that could be used for, but it's interesting to think about.

    I configured the device like this, which closely matches factory behaviour:
    
      P6 - LED_n 1  (the blue light on when the switch is off, and turns off to show the red light when switch is on)
      P7 - Btn 1
      P8 - AlwaysLow  (can't think what to do with this. It could be WifiLED_n, but it would be better if it were flashing for that)
      P9 - Btn 0
      P14 - Rel 1
      P24 - LED_n 0
      P26 - Rel 0
    
    Also to match default firmware:
      +Flag 6   ("Instant touch reaction instead of waiting for release")
      Startup state: -1, -1  (for both relays)
    

    Cool? Ranking DIY
    About Author
    TurkeyMan
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    TurkeyMan wrote 58 posts with rating 8. Been with us since 2022 year.
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