Dummy handler is invoked instead of the nrfx_uart_0_irq_handler upon a character being inserted in terminal

[morpho]

I'm trying to write the stripped down version of UART driver myself and having a few issues:

I enabled the UART, along with other registers as shown below

but when I enter a character in the terminal, I see the execution gets stuck on the following in the startup file. My initial assumption was the interrupt handler itself isn't being overridden in the application but I have it defined as shown below;

  .thumb_func
  .weak   Dummy_Handler
Dummy_Handler:
  b     .

void nrfx_uart_0_irq_handler(void)
{
    // do stuff
}

Both macros correspond to UARTE0_UART0_IRQHandler so that should be fine I guess.

#define nrfx_uart_0_irq_handler     UARTE0_UART0_IRQHandler





The call stack is as follows and the dummy handler is caused inside TIMER2_IRQHandler. Where is

TIMER2_IRQHandler being invoked from? And why does the nrfx_uart_0_irq_handler not get invoked instead?

Alsno note I have NRFX_PRS_ENABLED set to 0. Was getting a different error with that enabled

[hmolesworth]

Change this:

void nrfx_uart_0_irq_handler(void)
{
    // do stuff
}

to this:

void UARTE0_UART0_IRQHandler(void)
{
    // do stuff
}

This will now eclipse the weak definition:

.weak UARTE0_UART0_IRQHandler
.thumb_set UARTE0_UART0_IRQHandler, Dummy_Handler

If there are any #define conflicts simply comment them all out

[morpho]

tried that to no avail

[hmolesworth]

Did you comment out the useless macro stuff? Both are required, different files:

//#define nrfx_uart_0_irq_handler     UARTE0_UART0_IRQHandler

In ses_startup_nrf52.h:
.weak TIMER1_IRQHandler
//.thumb_set TIMER1_IRQHandler, Dummy_Handler

[morpho]

i did comment these lines out but now i see a WDT_IRQHandler being invoked.

[hmolesworth]

In that case just disable or better do not enable the watchdog; I don't know the project so can't advise on how, best if Nordic engineers guide on that.

[morpho]

Okay one thing I noticed: when I put the IRQ handler inside nrfx_uarte.c, it works but not when I put it inside my application. Also, I'm using C++. Do you see the relation?

[hmolesworth]

The linker will munch the name differently when placed in a .cpp file (munches) compared with c (no munch) I think, so now it doesn't match the assembler version. You can move the isr table into the C++ file to stop that. Better still just remove the weak definition entirely :-)