ATA Register Interface
MPC5200B Users Guide, Rev. 1
Freescale Semiconductor 11-11
11.3.2.5 ATA Rx/Tx FIFO Read Pointer Register—MBAR + 0x3A4C
11.3.2.6 ATA Rx/Tx FIFO Write Pointer Register—MBAR + 0x3A50
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 lsb
RReserved Alarm
W
RESET:000000000 0 0 000 0 0
Bits Name Description
0:19 — Reserved
20:31 Alarm User writes these bits to set low level “watermark”, which is the point where FIFO asserts
request for BestComm Controller data filling. Value is in bytes. For example, with Alarm = 32,
alarm condition occurs when FIFO contains 32Bytes or less. Once asserted, alarm d oes not
negate until high level mark is reached, as specified by FIFO control register granularity bits.

Table 11-17. ATA Rx /Tx FIFO Read Pointer Register

msb 012345678 9 101112131415
RReserved
W
RESET:000000000 0 0 000 0 0
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 lsb
RReserved ReadPtr
W
RESET:000000000 0 0 000 0 0
Bits Name Description
0:19 — Reserved
20:31 ReadPtr Value is maintained by FIFO hardware and is NOT normally written. It can be adjusted in
special cases, but this disrupts data flow integrity. Value represents the Read address
presented to the FIFO RAM.

Table11-18. ATA Rx/Tx FIFO Write Pointer Register

msb 012345678 9 101112131415
RReserved
W
RESET:000000000 0 0 000 0 0
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 lsb
RReserved WritePtr
W
RESET:000000000 0 0 000 0 0