stm32l0 serial2 not responding to interrupts on PA3

[sgabran]

Hi

I configured UART-2 to respond to interrupts.

If i use the RealTerm to write to the COMPORT of the STM (through the USB cable), the ISR works.

But, if I use usb-uart adaptor connected directly to PA3 (the UART-2 Rx pin), the ISR is not called.

If I replicate the same to UART-1, things work as expected.

Any clue what can be wrong ?

Thanks

[TDK]

> Any clue what can be wrong ?

Probably you're using a nucleo board and "PA3" on the connector isn't connected to the chip. Are you connecting it via the D0 header pin?

PA3 should be connected either to st-link VCP or to your USB-UART adapter, but not to both. You shouldn't have two things trying to drive it.

[sgabran]

yes, I am using the LoRa kit. We don't have access to UART-4-Rx or UART-5-Rx ( or Tx).

Is there a way we can connect PA3 to the chip ? any modification we can do ?

thanks

[Tesla DeLorean]

Which LoRa STM32L0 board ?

https://www.st.com/en/evaluation-tools/b-l072z-lrwan1.html

https://www.st.com/en/evaluation-tools/p-nucleo-lrwan1.html

Go to the CAD Resources Tab, pull a schematic, trace the wire, check solder-bridge options

[TDK]

Which part number are you using? Helps to put that in the opening post so the answers can be more informed.

[sgabran]

Hi, we are using the B-L072Z-LRWAN1.

So I think to be able to communicate directly with UART-2, I have to modify the eval-kit and desolder the bridge to STLink. But would I still be able to program the kit through STM-Cube ?

Thanks for your help

[TDK · Accepted solution]

Yes, you will still be able to program it, but the VCP line will no longer work.

The VCP isn't used for any programming functionality.

You'll need to take off SB28 so the line isn't driven by ST-Link anymore and you can drive it externally.