SWRU626 December 2025 CC3501E , CC3551E
In a DMA block write operation (single or multiple), the request signal SDMAWREQN is asserted to its active level when a complete block is to be written to the buffer. The block size transfer is specified in the SD_BLK[10:0] BLEN field.
The SDMAWREQN signal is deasserted to its inactive level when the DMA has written one single word to the buffer.
Only one request is sent per block; the DMA controller can make a 1-shot write access or multiple write DMA bursts, in which case the DMA controller must manage the number of burst accesses, according to block size BLEN field.
New DMA requests are internally masked if the DMA has not written exactly BLEN bytes (as DMA accesses are in 32-bit, then the number of DMA read is Integer(BLEN/4)+1) and if there is not enough memory space to write a complete block in the buffer.
Figure 20-11 provides a summary:
Figure 20-11 DMA
Transmit Mode