B-G431B-ESC1, ST-Link daughterboard, and RX TX n J5

[GHave.1]

I'm trying to use the RX / TX interface on J5 on the B-G431B-ESC1.

​However, it looks like the ST-LINK daughterboard uses those pins too.

I​ know I can snap off the daughterboard, but I still want to be able to use the ST MCSDK tools, switching back and forth as needed.

Unfortunately, a HW ​is a pain as the lines are simply shared and there's no good solder pads on the ST-LINK daughterboard and the ESC board to make a jumper.

What would be even better though, is being able to get the stm32 103 chip on th​e daughterboard to simply tri-state those lines when they are not being used.

If​ I don't power the daughterboard, the MCU drags the lines down too far, if I power through USB and / or 12v on the main + - pins for the motor and battery elimination circuit, then the 103 is actively trying to drive those lines, making the ones on J5 useless.

Any ideas?​

Is there any way to do this?​

[Gigi · Accepted solution]

Ciao

I'm looking the schematics of the board B-G431B-ESC1 but I see that the USART pin is mapped into J3 not in J5 (maybe is a typo).

 

Anyhow I think it is possible to unlink the USART pin of the main controller from the STLINK unsoldering these two resistors:

 

Ciao

Gigi

[GHave.1]

Yes, J3, J5/J6 are the power input pins on either side of J3.

I'll have to see if I can find where those resistors are on the board, I'm sure they're very tiny.

[Peter BENSCH]

R23 and R24 are easily found on the bottom side of the daughterboard:

Regards

/Peter