SMC256BFY6 STMICROELECTRONICS [STMicroelectronics], SMC256BFY6 Datasheet - Page 78

• Manufacturer Part Number: SMC256BFY6
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

CF-ATA command description
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Write DMA (CAh)
This command uses DMA mode to write from 1 to 256 sectors as specified in the Sector
Count register. If the sector count is set to ‘0’, 256 sectors will be read by issuing a Read
DMA command.
The transfer begins at the sector specified in the Sector Number Register. When the Write
DAM command is issued, the CompactFlash Storage Card asserts BSY and transfers all or
part of the sector data in the buffer. The Card can then set DRQ and clear BSY, although it is
not required.
The Card asserts DMARQ when data are available to be transferred. The host then writes
the 512*sector-count Bytes of data to the Card using the DMA protocol. When DMARQ is
asserted by the Card, the host asserts -DMACK to notify that it is ready to transfer data, and
asserts -IOWR once for each 16 bit Word to be transferred.
Interrupts are not generated for each sector transfer, but when all sectors have been
transferred or when an error occurred during the operation.
An Abort error is returned by the Card when a Write DMA command is sent by the host and
the 8-bit transfer mode has been enabled by the Set Features command.
Table 79
Table 79.
Command (7)
Sect Num (3)
Cyl High (5)
Sect Cnt (2)
Cyl Low (4)
Feature (1)
C/D/H (6)
Bit
defines the Write DMA command Byte sequence.
Write DMA
7
LBA
6
5
Cylinder High (LBA 23-16)
Sector Number (LBA 7-0)
Cylinder Low (LBA 15-8)
Drive
4
Sector Count
CAh
X
3
Head (LBA 27-24)
2
1
SMCxxxBF
0