Please help. I don't know where to connect RX, TX, GND, VDD 3.3V for the BK7231N device in order to flash it. Device: Aubess Power Monitor Switch. Thank you very much for your help. I apologize for my English.
Both the tutorials, either the chip has to be removed or PCB tack to be cut. How can I figure out if it is necessary for this device? I have several of these Power Monitor Switch (same exact PCB), I would really like to avoid taking the chip out.
If you have already a reliable flashing setup (good power supply, short wires, good USB to UART converter), then you can just solder RX,TX, ground and 3.3V (or 5V if you power through the AMS1117-3.3V on board) and just test. Do power off/on cycle via disconnecting your 3.3V/5V line and see if flasher gets bus.
Still, in general, flashing in circuit should work as long as your device does not have TuyaMCU connected on UART1 and as long as there are no capacitors on UART1 as well.
In this tutorial:
https://www.youtube.com/watch?v=PKkiqDNFIx8 We had to remove capacitor from UART1 lines in order to flash. That was a debouncing capacitor for button, not required in OBK.
Another possible issue that you may encounter while flashing in circuit is the large capacitance on the 5V line. If you are powering your device via 5V by feeding it to the input of AMS1117-3.3V to get 3.3V on WiFI module, and you do disconnect the power for a moment to do power off/on cycle, the large electrolytic capacitor may overload temporarily your USB power supply. This will be clearly indicated by a USB device disconnect sound, at least on windows. And UART Port will close as well.
>>21360761 Happy to report that I was able to flash OpenBK7231N in place without de-soldering the CB2S chip. I saw failure with baud rate 921600, switching to 115200 worked.
