[DMA] What happens if the stream is configured in circular (or double buffer mode) but the transfer direction is M2M?

[Jan561]

Hi,

As circular transfers are not allowed for memory-to-memory transfers, the following could happen:

• The MCU panics (i.e. hard fault)
• The CIRC and DBM-bit get forced low
• The CIRC and DBM-bit are being ignored

The reference manual only says that this is forbidden. For many other forbidden configurations it's documented that the problematic bit gets forced to the expected value.

Answers are appreciated.

EDIT: Following is unclear to me too: What happens if the Peripheral is the Flow Controller (i.e. PFCTRL is high), but DBM is high too?

PS: No, I can't try it by myself, because I don't own such a device.