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Tuya WB3S Pinout (BK7231T)

WB3S is an older Tuya module with the Beken BK7231T chip. It has the same package as the CB3S, but pins 10, 12, 13 and 14 are wired differently – so when flashing a device, it’s worth checking which module is actually inside.

Like the CB3S, it can be flashed with OpenBeken, LibreTiny or ESPHome.

Specifications

  • BK7231T: 32-bit Arm, Wi-Fi 4 (2.4 GHz) and Bluetooth LE
  • 2 MB flash
  • 22 pads in the ESP-12 format (16 × 24 mm), 6 of them on the bottom edge
  • 6 PWM channels, 1 analog input (P23), 2× UART and I2C
  • 3.3 V power

Flashing goes through UART1 (P10 RX, P11 TX) with reset via CEN. The pinout matches the LibreTiny database; compare it with the CB3S.

Pinout and pin table

Hover over a pin in the diagram or a table row; use the filter to highlight a bus. You can download the pinout as PNG or SVG.

Tuya WB3S (BK7231T) – pinoutTuya WB3S (BK7231T) – pinoutchiptron.eu · CC BY 4.0WB3SBK7231T 1 CEN → Reset – connecting to GND restarts the chip 2 P23 ADC3 TDO 3 CEN → 4 P14 SCK 5 P26 PWM5 6 P24 PWM4 7 P6 PWM0 8 3V3 → Power 3.3 V 16 P11 TX1 15 P10 RX1 14 P8 PWM2 13 P9 PWM3 12 P1 RX2 11 P0 TX2 10 P7 PWM1 9 GND 17 P23 ADC3 TDO 18 P22 TDI 19 P21 SDA1 TMS 22 NC 21 NC 20 P20 SCL1 TCK GPIO UART I2C SPI ADC (analog) PWM Power Ground (GND) Control / reset Not connected
Download:PNGSVG
License: CC BY 4.0 · How to credit
Pin table – Tuya WB3S (BK7231T)
PinNameDirectionUARTI2CSPIPWMADCNote
1CENinputReset (CEN, active low) – connecting to GND restarts the chip; when uploading via UART1 it is used to enter the bootloader
2P23input/outputADC3ADC3 – the only analog input; JTAG TDO; flash programming (FSO)
3CENinputReset (CEN, active low) – connecting to GND restarts the chip; when uploading via UART1 it is used to enter the bootloader
4P14input/outputSCK
5P26input/outputPWM5
6P24input/outputPWM4
7P6input/outputPWM0
83V3inputPower 3.3 V
9GND–
10P7input/outputPWM1
11P0input/outputTX2SCL2UART2 TX – log output; I2C2 SCL
12P1input/outputRX2SDA2UART2 RX; I2C2 SDA
13P9input/outputPWM3
14P8input/outputPWM2
15P10input/outputRX1UART1 RX – firmware upload (bk7231tools, ltchiptool, OpenBeken)
16P11input/outputTX1UART1 TX – firmware upload
17P23input/outputADC3ADC3 – the only analog input; JTAG TDO; flash programming (FSO)
18P22input/outputJTAG TDI; flash programming via SPI (FSI)
19P21input/outputSDA1I2C1 SDA; JTAG TMS; flash programming via SPI (FCS). Must not be at logic 0 at power-up (test mode)
20P20input/outputSCL1I2C1 SCL; JTAG TCK; flash programming via SPI (FSCK)
21NC–
22NC–

What to watch out for

  • Disconnect the device from the 230 V mains before opening it. Program the module only from a 3.3 V USB-serial converter.
  • Before overwriting the firmware, back up the original flash contents.
  • Pins 10, 12, 13 and 14 differ from the CB3S – device templates for the CB3S don’t fit the WB3S.
  • When flashing, briefly connect CEN to GND (reset) and connect the converter to P10/P11.

More pinouts

See all pinouts on the Pinouts page.

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