PM5381-BI PMC-Sierra, Inc., PM5381-BI Datasheet - Page 410

• Manufacturer Part Number: PM5381-BI
• Description: ATM UNI, Single Channel ATM PHY Interface for 2488.32Mbps
• Manufacturer: PMC-Sierra, Inc.

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000489, Issue 4
Register 077AH: TXSDQ FIFO Indirect Data and Buffer Available Thresholds
This register is used to set the Data and Buffer Available Thresholds for a FIFO. These thresholds
are explained in the Operation section. A FIFO does not need to be enabled to set this threshold.
In order to change a value for a FIFO, the user should first disable it, write in the new value, and
enable it again. See section 13.8: RXSDQ and TXSDQ Data Available and Burst-Size Operation
for more information on configuring the TXSDQ, RXSDQ, TXPHY, and RXPHY. This register
must be accessed via an indirect register read or write via register 0778H. See also section 13.19:
Accessing Indirect Registers.
BT[4:0]
Bit
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
These bits specify the Buffer Available threshold for the FIFO specified in PHYID[5:0] bits
in the TXSDQ FIFO Indirect Address register. When this threshold is being set, these bits are
written to by the user, and when this threshold is being read, these bits hold the previously
configured data. The threshold is equal to BT[4:0] + 1.
This threshold is set in 16 byte Blocks. This threshold can never be greater than the size of
the FIFO being configured, and the absolute maximum value is BT[4:0] +1 = 32. This
number should be a standard fraction of the FIFO size in blocks. In the case of ATM FIFOs,
this number should be set to a value of BT[4:0] = 3 since ATM cells are 4 blocks in size.
Type
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
DT[7]
DT[6]
DT[5]
DT[4]
DT[3]
DT[2]
DT[1]
DT[0]
BT[4]
BT[3]
BT[2]
BT[1]
BT[0]
Function
Unused
Unused
Unused
S/UNI-2488 Telecom Standard Product Datasheet
Default
0
0
0
0
0
0
1
1
X
X
X
0
0
0
1
1
Released
410