Integrated DMA

(Ask a Question)

The SD Host controller supports two DMA modes:

The following table shows how to select the DMA engine and Addressing mode by setting SRS10.DMASEL, SRS15.HV4E and SRS16.A64S register fields.

Table 1. DMA Mode
SRS10.DMASEL SRS15.HV4E SRS16.A64S DMA Mode
0 0 0 SDMA 32-bit
1 Reserved
1 0 SDMA 32-bit
1 SDMA 64-bit
1 0 0 Reserved
1 Reserved
1 0 Reserved
1 Reserved
2 0 0 ADMA2 32-bit
1 Reserved
1 0 ADMA2 32-bit
1 ADMA2 64-bit
3 0 0 Reserved
1 ADMA2 64-bit
1 0 Reserved
1 Reserved

The DMA transfer in each mode can be stopped by setting Stop at the Block Gap Request bit (SRS10.SBGR). The DMA transfers can be restarted only by setting Continue Request bit (SRS10.CREQ). If an error occurs, the Host Driver can abort the DMA transfer in each mode by setting Software Reset for DAT Line (SRS11.SRDAT) and issuing Abort command (if a multiple block transfer is executing).