Hardware Trigger, SIRQ

A hardware trigger is an interrupt request from another module sent to the DMA with the purpose of starting a DMA message. The DMA start trigger source is user-selectable using the DMAnSIRQ register.

The SIRQEN bit is used to enable sampling of external interrupt triggers by which a DMA transfer can be started. When set, the DMA will sample the selected interrupt source and when cleared, the DMA will ignore the interrupt source. Clearing the SIRQEN bit does not stop a DMA transaction currently in progress, it only stops more hardware request signals from being received.