Datasheet

ATA/ATAPI Interface Port
11−26
SLLS535E − March 2008TUSB6250
11.6.15 SECRDPTH: Sector FIFO Read Pointer High-Byte Register (XDATA at F0F0)
76543210
RSV RSV RD_PTR13 RD_PTR12 RD_PTR11 RD_PTR10 RD_PTR9 RD_PTR8
R/O R/O R/O R/O R/O R/O R/O R/O
BIT
NAME RESET FUNCTION
5−0 RD_PTR[13:8] 000000 These bits contain the sector FIFO read pointer higher 6-bit value. Read-only
The sector FIFO controller uses RD_PTR[13:0] as the current read pointer to read data out
from sector FIFO.
 When the UBM reads the data from the sector FIFO and transmits the data to USB,
meanwhile there is an ACK timeout, the UBM rewinds the read pointer by copying
RD_PTR_BK[13:0] back to RD_PTR[13:0].
 If the ATA/ATAPI side reads the data from the sector FIFO, the read pointer cannot be
rewound.
 After each read from the ATA side, RD_PTR[13:0] is incremented by 1 and the new value
is copied into RD_PTR_BK[13:0].
7−6 RSV 00 Reserved
11.6.16 RDPTBKUPL: Sector FIFO Read Pointer Backup Low-Byte Register (XDATA at
F0F1)
7 6543210
RD_PTR_BK7 RD_PTR_BK6 RD_PTR_BK5 RD_PTR_BK4 RD_PTR_BK3 RD_PTR_BK2 RD_PTR_BK1 RD_PTR_BK0
R/O R/O R/O R/O R/O R/O R/O R/O
BIT
NAME RESET FUNCTION
7−0 RD_PTR_BK[7:0] 00h This register contains the confirmed sector FIFO read pointer lower 8-bit value. Read-only
11.6.17 RDPTBKUPH: Sector FIFO Read Pointer Backup High-Byte Register (XDATA at
F0F2)
76543210
RSV RSV RD_PTR_BK13 RD_PTR_BK12 RD_PTR_BK11 RD_PTR_BK10 RD_PTR_BK9 RD_PTR_BK8
R/O R/O R/O R/O R/O R/O R/O R/O
BIT
NAME RESET FUNCTION
5−0 RD_PTR[13:8] 000000 These bits contain the confirmed sector FIFO read pointer higher 6-bit value. Read-only.
RD_PTR[13:0] allows the UBM to retransmit a data packet if an ACK timeout occurs.
 When the UBM transmit packet gets ACKed, the sector FIFO controller copies the
RD_PTR[13:0] to RD_PTR_BK[13:0].
 When the UBM must retransmit the packet, the sector FIFO controller copies the
RD_PTR_BK[13:0] back to RD_PTR[13:0] to reset the read pointer.
7−6 RSV 00 Reserved