The STM has a DMA peripheral request interface designed to function with an AMBA DMA Controller DMA-330. This interface enables the STM to request writes to be made to its extended stimulus ports by the DMA controller. You must set up and program the DMA controller with the required transactions before this functionality is enabled in the STM. See the AMBA DMA Controller DMA-330 Technical Reference Manual for more information about the specification of this interface.