Datasheet

SAM9G45 [DATASHEET]
Atmel-6438O-ATARM-SAM9G45-Datasheet_08-Dec-15
816
35.14.16 HSMCI DMA Configuration Register
Name: HSMCI_DMA
Address: 0xFFF80050 (0), 0xFFFD0050 (1)
Access: Read/Write
This register can only be written if the WPEN bit is cleared in “HSMCI Write Protect Mode Register” on page 818.
• OFFSET: DMA Write Buffer Offset
This field indicates the number of discarded bytes when the DMA writes the first word of the transfer.
• CHKSIZE: DMA Channel Read and Write Chunk Size
The CHKSIZE field indicates the number of data available when the DMA chunk transfer request is asserted.
• DMAEN: DMA Hardware Handshaking Enable
0: DMA interface is disabled.
1: DMA Interface is enabled.
Note: To avoid unpredictable behavior, DMA hardware handshaking must be disabled when CPU transfers are performed.
• ROPT: Read Optimization with padding
0: BLKLEN bytes are moved from the Memory Card to the system memory, two DMA descriptors are used when the trans-
fer size is not a multiple of 4.
1: Ceiling(BLKLEN/4) * 4 bytes are moved from the Memory Card to the system memory, only one DMA descriptor is used.
31 30 29 28 27 26 25 24
––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––ROPT–––DMAEN
76543210
–– CHKSIZE –– OFFSET
Value Name Description
00 1 1 data available
01 4 4 data available
10 8 8 data available
11 16 16 data available