Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Fiche De Données

582

SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

6.

The LLI_W(n).DMAC_DADDRx field in the memory must be word aligned.

7.

Configure the fields of LLI_W(n).DMAC_CTRLAx as follows:

–DST_WIDTH is set to WORD.

–SRC_WIDTH is set to WORD.

–SCSIZE must be set according to the value of HSMCI_DMA, CHKSIZE field.

–BTSIZE is programmed with block_length/4. If BTSIZE is zero, this descriptor is skipped later.

8.

Configure the fields of LLI_W(n).DMAC_CTRLBx as follows:

–DST_INCR is set to INCR.

–SRC_INCR is set to INCR.

–FC field is programmed with peripheral to memory flow control mode.

–SRC_DSCR is set to 0 (descriptor fetch is enabled for the SRC).

–DST_DSCR is set to TRUE (descriptor fetch is disabled for the DST).

–DIF and SIF are set with their respective layer ID. If SIF is different from DIF, the DMA Controller is 

able to prefetch data and write HSMCI simultaneously.

9.

Configure the fields of LLI_W(n).DMAC_CFGx for Channel x as follows:

–FIFOCFG defines the watermark of the DMA channel FIFO.

–DST_REP is set to zero. Address are contiguous.

–SRC_H2SEL is set to true to enable hardware handshaking on the destination.

–SRC_PER is programmed with the hardware handshaking ID of the targeted HSMCI Host 

Controller.

10. Program LLI_W(n).DMAC_DSCRx with the address of LLI_B(n) descriptor. And set the DSCRx_IF to the 

AHB Layer ID. This operation actually links the Word oriented descriptor on the second byte oriented 
descriptor. When block_length[1:0] is equal to 0 (multiple of 4) LLI_W(n).DMAC_DSCRx points to 0, only 
LLI_W(n) is relevant.

11. Program the channel registers in the Memory for the second descriptor. This descriptor will be byte oriented. 

This descriptor is referred to as LLI_B(n), standing for LLI Byte oriented.

12. The LLI_B(n).DMAC_SADDRx field in memory must be set with the starting address of the HSMCI_FIFO 

address.

13. The LLI_B(n).DMAC_DADDRx is not relevant if previous word aligned descriptor was enabled. If 1, 2 or 3 

bytes are transferred, that address is user defined and not word aligned.

14. Configure the fields of LLI_B(n).DMAC_CTRLAx as follows:

–DST_WIDTH is set to BYTE.

–SRC_WIDTH is set to BYTE.

–SCSIZE must be set according to the value of HSMCI_DMA, CHKSIZE field.

–BTSIZE is programmed with block_length[1:0]. (last 1, 2, or 3 bytes of the buffer).

15. Configure the fields of LLI_B(n).DMAC_CTRLBx as follows:

–DST_INCR is set to INCR.

–SRC_INCR is set to INCR.

–FC field is programmed with peripheral to memory flow control mode.

–Both SRC_DSCR and DST_DSCR are set to 1 (descriptor fetch is disabled) or Next descriptor 

location points to 0.

–DIF and SIF are set with their respective layer ID. If SIF is different from DIF, the DMA Controller is 

able to prefetch data and write HSMCI simultaneously.