DMA: last written buffer position?

[PRenn.1]

DMA buffer 32 words, ADS converts 4 channels in scan mode.
So every 8 ADC-starts  DMA will start at buffer[0]  (circular buffer is ticked).
CubeIDE HAL is being used.

How do I find out / look up  the buffer offset most recently written to?

[MasterT]

Look into DMA registers, there is a counter

[tjaekel]

If you use DMA and the callbacks (for Half or Full) - you should know where you are (which buffer was filled recently).

Yes, you might be able to read back also DMA registers (e.g. address pointer). Easier is to use callbacks, double buffering and knowing when DMA INT comes which buffer was (completely) written...

[nicolas]

There is a macro named __HAL_DMA_GET_COUNTER(handle) that returns the number of remaining data bytes in the current DMA Channel transfer.

[PRenn.1]

We need to clarify some vocabulary first:  Do you mean

the remaining data bytes the currently active DMA transfer still has to copy
(of a 4 conversions ADC session, 2 conversion still outstanding)

or

the remaining data bytes in the assigned DMA destination buffer (in "user" memory)
before cyclic DMA transfer will wrap back to start of buffer ?

[MasterT]

It's second. Just try, making slow sampling rate (~1 sec) you can observe all processes in details.