
IBM2520L8767
IBM Processor for ATM Resources
Reset and Power-on Logic (CRSET)
Page 388 of 553
atmrm.chapt05.01
08/27/99
20.7: Clock Control Register (Nibble Aligned)
Used to disable clocks for power conservation and provide the "Select A Clock" function for MPEG and front
end support. To change a nibble field in this register, ALWAYS set it to zero first, and then to the new value.
Length
29 bits
Type
Read/Write
Address
XXXX 0520
POR Value
X’6676632’
F
(
Encoded
ControlforBIST
Speed
Reserved
(Encoded Con-
trol for PCORE
Clock Rate)
Encoded
Control for Vari-
ous On-Chip
Functions
Encoded
Control for Cell
Opportunity
Logic (CELLO)
Encoded
Control for
MPEG
Clocking Logic
(MPEGT)
Encoded
Control for
Transmit Logic
(LINKT) and
Sonet Framer
(FRAMR)
Encoded
Control for
Receive Logic
(LINKR) and
Sonet Framer
(FRAMR)
28
27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Bit(s)
Name
Description
28)
Framer Tree Disabled (FRAMR)
When set this bit will disable the clock tree to the Sonet Framer
Logic.
27-24
Encoded Control for BIST Speed
Hardcoded to 6.
23-20
Reserved (for Encoded Control for PCORE Clock
Rate.)
Hardcoded to 6.
19-16
Encoded Control for Various On Chip TimeStamp
Logic (RXQUE,etc.)
Same as bits 3-0.
15-12
Encoded Control for Cell Opportunity Logic (CELLO)
Same as bits 3-0.
11-8
Encoded Control for MPEG Clocking Logic (MPEGT)
Same as bits 3-0.
7-4
Encoded Control for Transmit Logic (LINKT) and
Sonet Framer (FRAMR)
Same as bits 3-0.
3-0
Encoded Control for Receive Logic (LINKR) and
Sonet Framer (FRAMR)
Below is the encoded value of the bits that select a given clock.
Always refer to
Select A Clock" Selection Matrix
on page 389
for
inputs supported for each clock out type.
X’0’
Turn this clock off.
X’1’
Use the external MPEG oscillator.
X’2’
Use the external RX clock.
X’3’
Use the external TX clock.
X’4’
Use the internal 15-ns clock. Assumes 33-MHz PCI clock.
X’5’
Use the internal 20-ns clock. Assumes 33-MHz PCI clock.
X’6’
Use the internal 30-ns clock. Assumes 33-MHz PCI clock.
X’7’
Use the internal 60-ns clock. Assumes 33-MHz PCI clock.
X’8’
Use the internal 120-ns clock. Assumes 33-MHz PCI clock.
X’9’
Use the internal 240-ns clock. Assumes 33-MHz PCI clock.
X’A’
Use the internal 480-ns clock. Assumes 33-MHz PCI clock.
X’B’
Use the differential Receiver clock divided by 8.
]X’C’ Use the differential Transmit clock divided by 8.