FAQ
TL;DR: 5–24 V input, BK7231N-based; "Use TP5 for RX and TP4 for TX." This 12V barrel smart switch opens via four clips, flashes reliably with 12 V power, and exposes button P14 and LED Cool on P8. [Elektroda, OxygenDesk, post #21043447]
Why it matters: For tinkerers re-flashing BK7231N 12V barrel switches, this FAQ shows safe access, GPIO mapping, and backup steps.
Quick Facts
- Module/MCU: Tuya CB3S with BK7231N; PCB silkscreen: “DLX-RGBCW BK7231N-B 5–24V.” [Elektroda, OxygenDesk, post #21043447]
- Power: Printed 5–24 V input; device flashed successfully while powered with 12 V via the barrel jack. [Elektroda, OxygenDesk, post #21043447]
- UART pads: TP5 = RX, TP4 = TX; case opens by prying near the strain relief; four clips hold it. [Elektroda, OxygenDesk, post #21043447]
- GPIO mapping: Button wired to P14; LED Cool (Channel 4) on P8; OpenBeken didn’t auto-detect the button. [Elektroda, OxygenDesk, post #21043447]
- Flashing tool: BK7231GUIFlashTool’s “Do backup and flash new” is recommended; “no backup” is not. [Elektroda, p.kaczmarek2, post #21177108]
What’s inside this 12V smart switch (MCU, module, markings)?
It uses a BK7231N on a Tuya CB3S module. PCB silkscreen reads “DLX-RGBCW BK7231N-B 5–24V.” The board shows pads for three additional light channels, though connectivity wasn’t verified. This aligns it with Tuya RGB/CW designs. [Elektroda, OxygenDesk, post #21043447]
How do I open the case without damage?
Pry near the wire strain relief with a small flathead screwdriver. Four internal clips hold the shell together. Work around the seam to release each clip. The enclosure opens cleanly for access to the CB3S module and test pads. [Elektroda, OxygenDesk, post #21043447]
Which pads are TX/RX for UART flashing, and how should I power it?
Use TP5 for RX and TP4 for TX. Provide external power while flashing. The board was powered with 12 V through the barrel connector, matching the printed 5–24 V input range. [Elektroda, OxygenDesk, post #21043447]
What’s the best tool and a safe 3-step way to back up and flash?
Use BK7231GUIFlashTool. “Best option for flashing this device,” notes the maintainer. How-To: 1. Pick “Do backup and flash new.” 2. Connect power and UART to the module. 3. Run backup, then flash firmware. Avoid the “no backup” option. [Elektroda, p.kaczmarek2, post #21177108]
Does the full 2 MB backup include the 72 KB Tuya config?
Yes. “The 2MB backup file already contains that 72KB file.” One dump covers the firmware and the Tuya config block. This confirms a single archive preserves your settings snapshot. [Elektroda, p.kaczmarek2, post #21044231]
Which GPIOs control the button and LED in this unit?
The button is on P14. The Tuya-extracted config maps LED Cool (Channel 4) to P8. OpenBeken did not auto-detect the button, so manual assignment is required on this unit. [Elektroda, OxygenDesk, post #21043447]
Will ESPHome run, and what worked after flashing?
Yes. The user reflashed to ESPHome and confirmed, “the button works and the light dims.” This validates basic input and dimming control on the hardware. For configuration, align with the noted pin mapping. [Elektroda, OxygenDesk, post #21045133]
OpenBeken didn’t detect my button—how do I fix it?
Map the button manually. On this device, the button line is P14. If auto-detection misses it, set P14 as the button in your template. [Elektroda, OxygenDesk, post #21043447]
How should I power the board during flashing?
Use external power. The board accepted 12 V through the barrel jack during flashing. The PCB print states a 5–24 V input range. [Elektroda, OxygenDesk, post #21043447]
Can I use the extra RGB/CW channels on the PCB?
The PCB has footprints for three additional light channels. The author did not verify whether those channels are wired. Treat them as unpopulated unless you trace them yourself. [Elektroda, OxygenDesk, post #21043447]
Where does the Tuya config block start in the dump?
The author noted the Tuya section begins at offset 2023424 in the binary. This can help when parsing a raw backup for GPIO data. [Elektroda, OxygenDesk, post #21043447]
How was the device shipped (any branding or packaging)?
The unit arrived in a yellow envelope without packaging or branding. Expect minimal protection and no brand identification on arrival. [Elektroda, OxygenDesk, post #21043447]
![[BK7231N] 12V Smart Switch Teardown](https://obrazki.elektroda.pl/3160981300_1712968570.jpg "[BK7231N] 12V Smart Switch Teardown")
![[BK7231N] 12V Smart Switch Teardown](https://obrazki.elektroda.pl/7160639900_1712968570.jpg "[BK7231N] 12V Smart Switch Teardown")
![[BK7231N] 12V Smart Switch Teardown](https://obrazki.elektroda.pl/4744902900_1712968570.jpg "[BK7231N] 12V Smart Switch Teardown")
![[BK7231N] 12V Smart Switch Teardown](https://obrazki.elektroda.pl/6915218600_1712968576.jpg "[BK7231N] 12V Smart Switch Teardown")
![[BK7231N] 12V Smart Switch Teardown](https://obrazki.elektroda.pl/7535502300_1712968584.jpg "[BK7231N] 12V Smart Switch Teardown")
