16.3 DMA Interface
The DMA module transfers data from the source to the destination one byte at a time, this smallest data movement is called a DMA data transaction. A DMA message refers to one or more DMA data transactions.
- Reading the source address memory and storing the value in the DMA Buffer register
- Writing the contents of the DMA Buffer register to the destination address memory
The XIP bit is a Status bit to indicate whether or not the data in the DMAnBUF register has been written to the destination address. If the bit is set, then data is waiting to be written to the destination. If clear, it means that either data has been written to the destination or that no source read has occurred.
The DMA has read access to PFM, Data EEPROM, and SFR/GPR space, and write access to SFR/GPR space. Based on these memory access capabilities, the DMA can support the following memory transactions:
Read Source | Write Destination |
---|---|
Program Flash Memory | GPR |
Program Flash Memory | SFR |
Data EE | GPR |
Data EE | SFR |
GPR | GPR |
GPR | SFR |
SFR | GPR |
SFR | SFR |
The following sections discuss the various control interfaces required for DMA data transfers.