8 Peripheral DMA

The peripheral direct memory access (PDMA) is an AHB master associated with the AHB bus matrix, as shown in the following figure. The PDMA allows data transfers from various MSS peripherals to memory, memory to various peripherals, and memory to memory. The peripheral can be MSS peripheral (MMUART, CAN, SPI, and COMM_BLK) or fabric peripheral (FIC_0 and FIC_1). The memory can be MSS memory (eNVM_0, eNVM_1, eSRAM_0, and eSRAM_1) or fabric internal memory (LSRAM and µSRAM) or external memory connected to fabric.

The PDMA is typically used for off loading byte-intensive operations and involving peripherals from the Cortex-M3 processor. For example, the firmware could direct the PDMA to transfer the next 1,000 characters received on one of the MMUARTs to eSRAM and notify the processor when ready.