How to Toggle a Debug Pin When ADC Conversion Starts in DMA Mode on STM32?

[BitCurious]

Hello,
I am working with an STM32 G4 series microcontroller and using the ADC in DMA mode to handle continuous conversions. My goal is to SET a GPIO (debug pin) at the start of an ADC conversion and RESET it at the end of the conversion.

Currently, I am able to RESET the GPIO pin in the HAL_ADC_ConvCpltCallback() function, which is called after the conversion completes. However, since DMA mode doesn't involve regular polling or interrupt-based conversions for the start, I am unsure where to place the GPIO SET code.

Here are the details of my setup:

• ADC Trigger Source: TIM2
• TIM2 Configuration: FCLK = 60 MHz, PSC = 0, ARR = 469 (Triggering ADC at ~128 kHz).
• DMA Mode: Circular, 12-bit resolution.

Is there a recommended way to toggle or set a debug pin when the ADC conversion process starts? Would I need to modify the HAL driver, or is there a way to do this using timer-based callbacks or HAL functions?

Any guidance, examples, or best practices would be greatly appreciated.

Thank you!

[TDK]

Since your sampling is tied to the timer, you could set channel 1 of the timer to go high/low at the times the ADC samples, but you would have to know these times and set them explicitly.

There's no way to call code at the exact moment the ADC starts sampling with DMA. Nor is there a way to tie code at the exact moment sampling stops. HAL_ADC_ConvCpltCallback happens after sampling, but quite a bit after it.