2 years, 9 months ago.

Explicit interrupt handler attach required in C++, but not C? (Nucleo-32F042)

I'm working with a UART console in MBED OS2 using STMicro's HAL libraries as opposed to the MBED Serial class. I could not get receive to work(the RX handler was not getting called, and further evidence showed that the program was going "in the weeds" on a receive character. I decided to make a small test program just to echo characters received, all in one main.c file. It works, however, if I change just the name of the file to main.cpp, RX stops working. After a lot of trial and error I found that adding this:

NVIC_SetVector(USART2_IRQn, (uint32_t)&USART2_IRQHandler); Attach interrupt handler

to the init code then fixed the RX operation. I thought USART2_IRQHandler, was a default predefined handler(somewhere in the STM32 HAL). Why do I get the attach for "free" in C, but in C++, I'm required to call NVIC_SetVector? This may be a STM HAL specific thing but I thought I'd post it here to see if anyone knew the "why" and so anyone else having this issue would have something to try that worked for me...

1 Answer

2 years, 8 months ago.

Hello Douglas,

Can you take a look at this question and see if it is relevant to what you are looking for?:


Looks like it could be due to C vs C++ name mangling. Hope this helps!

-Karen, team Mbed

If this solved your question, please make sure to click the "Thanks" link below!

Accepted Answer

Yes, indeed. This does appear to be the issue. Thanks for the link. I've save it to PDF to put in my "folder of wisdom"!

posted by Douglas S 27 Jul 2018