DMA Support - IRQ Handlers in Core?

[xC0000005]

While trying to get some LEDs working with the ST Arduino core, I ran into a problem that's likely a missing feature. Libraries probably shouldn't be implementing the weak IRQ handlers, because you can't have them defined everywhere. In my own fork, I added, similar to timers, handlers with registration/deregistration. For things like ADC and SD Support, this would be handy, but I'm not sure if there's a plan for this. I could create a PR, but I'd rather see what the consensus is.

Link to a branch with some test DMA support (ignore the library - I'm not sure how I want it to work, so it's not even remotely usable).

https://github.com/xC0000005/Arduino_Core_STM32/tree/DMASupport

[fpistm]

Hi @xC0000005
DMA support would be fine.
Currently, I have no plan about that. Any contribution are welcome.
Do not hesitate to proposal a PR (you can set it as Draft) to open discussion about your proposal.

[4ndreas]

I had the same problem, that you can not add IRQ functions in the arduino code (Also for DMA). My work around was to add a new board variant with the IRW functions. This is not perfect but at least I don't have to fork the hole core.
Adding IRW functions to the variant.c works for me.

[fpistm]

Hi @4ndreas

I had the same problem, that you can not add IRQ functions in the arduino code (Also for DMA).

I guess you talk about adding an IRD handler in the sketch ? Did you define it with extern "c" ?

[4ndreas]

No In my case I needed the

 void DMA2_Stream2_IRQHandler(void)
 {
   /* USER CODE BEGIN DMA2_Stream2_IRQn 0 */

   /* USER CODE END DMA2_Stream2_IRQn 0 */
   HAL_DMA_IRQHandler(&hdma_tim8_ch1);
   /* USER CODE BEGIN DMA2_Stream2_IRQn 1 */

   /* USER CODE END DMA2_Stream2_IRQn 1 */
 }

Function, adding this in the *.ino files won't work, but in the variant.c does. Took me a while to figure out why the interrupt jumped to a wired position.

The complet project is here: https://github.com/4ndreas/HyperLight_DMA
It uses DMA to GPIO to drive WS2812 leds

[fpistm]

At sketch level it should be:
extern "C" void DMA2_Stream2_IRQHandler(void)

Note:
In your case, I guess a library would be a best choice.
the Adafruit Neopixel library is now compatible with the STM32 core.

[4ndreas]

At sketch level it should be:
extern "C" void DMA2_Stream2_IRQHandler(void)

Note:
In your case, I guess a library would be a best choice.
the Adafruit Neopixel library is now compatible with the STM32 core.

That is something for the Wiki I gues, thank you.
My driver drives 16 strips up top 1000 leds in parallel. The DMA controller is perfect for this.

[xC0000005]

I'll open a PR this week. The goal is simple - have sketches not defining handlers for events that are global to the core, so libraries can register for different DMA events without having conflicting handlers. Thanks for the input, all.

[xC0000005]

Opened #825 since a suggested change is better than a dozen posts about what we could do.