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