SST55LC100 Datasheet, PDF (44/80 Pages) Silicon Storage Technology, Inc – CompactFlash Card Controller

Advance Information
9.2.6.37 Read-Multiple - C4H
CompactFlash Card Controller
SST55LC100
Bit ->
7
6
5
4
3
2
1
0
Command (7)
C4H
C/D/H (6)
1
LBA
1
Drive
Head (LBA 27-24)
Cyl High (5)
Cylinder High (LBA 23-16)
Cyl Low (4)
Cylinder Low (LBA 15-8)
Sec Num (3)
Sector Number (LBA 7-0)
Sec Cnt (2)
Sector Count
Feature (1)
X
Note: The current revision of the CompactFlash card controller can support up to a block count of 1 as indicated in the Identify-Drive
Command information.
The Read-Multiple command is similar to the Read-Sector(s) command. Interrupts are not generated
on every sector, but on the transfer of a block which contains the number of sectors defined by a Set
Multiple command.
Command execution is identical to the Read-Sectors operation except that the number of sectors
defined by a Set Multiple command are transferred without intervening interrupts. DRQ qualification of
the transfer is required only at the start of the data block, not on each sector.
The block count of sectors to be transferred without intervening interrupts is programmed by the Set-
Multiple-Mode command, which must be executed prior to the Read-Multiple command. When the
Read-Multiple command is issued, the Sector Count register contains the number of sectors (not the
number of blocks or the block count) requested. If the number of requested sectors is not evenly
divisible by the block count, as many full blocks as possible are transferred, followed by a final, partial
block transfer. The partial block transfer is for n sectors, where
n = remainder (sector count/block count).
If the Read-Multiple command is attempted before the Set-Multiple-Mode command has been executed
or when Read-Multiple commands are disabled, the Read-Multiple operation is rejected with an
Aborted Command error. Disk errors encountered during Read-Multiple commands are posted at the
beginning of the block or partial block transfer, but DRQ is still set and the data transfer will take place
as it normally would, including transfer of corrupted data, if any.
Interrupts are generated when DRQ is set at the beginning of each block or partial block. The error
reporting is the same as that on a Read-Sector(s) command. This command reads from 1 to 256
sectors as specified in the Sector Count register. A sector count of 0 requests 256 sectors. The transfer
begins at the sector specified in the Sector Number register.
At command completion, the Command Block registers contain the cylinder, head and sector number of
the last sector read.
If an error occurs, the read terminates at the sector where the error occurred. The Command Block
registers contain the cylinder, head and sector number of the sector where the error occurred. The
flawed data is pending in the sector buffer.
Subsequent blocks or partial blocks are transferred only if the error was a correctable data error. All
other errors cause the command to stop after transfer of the block which contained the error.
©2005 Silicon Storage Technology, Inc.
44
S71298-00-000
10/05