29-59
MPC8260 PowerQUICC II UserÕs Manual
MOTOROLA
Part IV. Communications Processor Module
4Ð6
Ñ
Reserved, should be cleared.
7
CP-TA
Cell loss priorityÐturn-around cell. Holds the CLP of the last received F-RM cell. If another
F-RM cell arrives before the previous one was turned around, CP-TA is overwritten by the
new RM cellÕs CLP.
8Ð9
Ñ
Reserved, should be cleared.
10
CI-VC
Congestion indication -VC. Holds the EFCI (explicit forward congestion indication) of the
last user data cell. The CI bit of the turned around RM cell is ORed with the CI-VC.
Initialize to 0.
11Ð15
Ñ
Reserved, should be cleared.
0x08
Ñ
MCR
Minimum cell rate Holds the minimum number of cells/sec of the current ABR channel.
Uses the ATMF TM 4.0 ßoating-point format.
0x0A
Ñ
UNACK
Used by the CP to count F-RM cells sent in an absence of received B-RM cells. Initialize to
0.
0x0C
Ñ
ACR
Allowed cell rate The cells per second allowed for the current ABR channel. Uses the
ATMF TM 4.0 ßoating-point format. Initialize with ICR.
0x0E
0
ACRC
ACR change. Indicates a change in ACR. Initialize to one.
1Ð15
Ñ
Reserved, should be cleared.
0x10
Ñ
RCTS
RM cell time stamp. Used exclusively by the CP. Initialize to zero.
0x14
0
FRST
First turn. Used exclusively by the CP. Indicates the Þrst turn of a backward RM cell, which
has priority over a data cell. Initialized to 0.
1Ð3
Ñ
Reserved, should be cleared.
4Ð7
CDF
Cutoff decrease factor. Controls the decrease in the ACR associated with missing B-RM
cells feedback. CDF represents a negative exponent of two, that is, the cutoff decrease
factor = 2
-CDF
. The cutoff decrease factor ranges from 1/64 (CDF=0b0110) to 1
(CDF=0b0000). All other CDF values falling outside this range are invalid.
8Ð15
COUNT Count. Used only by the CP. Holds the number of cells sent since the last forward RM cell.
Initialize with Nrm (in the parameter RAM).
0x16
Ñ
ICR
Initial cell rate. The number of cells per second of the current ABR channel. The channelÕs
ACR is initialized with ICR. ICR uses the ATMF TM 4.0 ßoating-point format.
0x18
Ñ
CRM
Missing RM cells count. Limits the number of forward RM cells that may be sent in the
absence of received backward RM cell. The CRM is in units of cells.
0x1A
Ñ
ADTF
ADTFÐACR decrease time factor. The ADTF period is 500 ms as deÞned in the TM 4.0.
The ADTF value is deÞned by the system clock and the time stamp timer prescaler; see
Section 13.3.7, ÒRISC Time-Stamp Control Register (RTSCR).Ó For a time stamp prescaler
of 1 µs, ADTF should be programmed to 500m/(1µs
´
1024)= 488.
0x1C
Ñ
ER
Explicit rate. Holds the explicit rate value (in cells/sec) of the current ABR channel. ER is
copied to the F-RM cell ER Þeld. The user usually initializes this Þeld to PCR. ER uses the
ATMF TM 4.0 ßoating-point format.
0x1E
Ñ
ER-BRM Explicit rate-backward RM cell. Holds the maximum explicit rate value (in cells/sec)
allowed for B-RM cells. The ER-TA Þeld which is inserted to each B-RM cell is limited by
this value. ER-BRM uses the ATMF TM 4.0 ßoating-point format.
Table 29-27. ABR-Specific TCTE Field Descriptions (Continued)
Offset
Bits
Name
Description
Summary of Contents for MPC8260 PowerQUICC II
Page 1: ...MPC8260UM D 4 1999 Rev 0 MPC8260 PowerQUICC II UserÕs Manual ª ª ...
Page 66: ...lxvi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA ...
Page 88: ...1 18 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 120: ...2 32 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 138: ...Part II iv MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II Configuration and Reset ...
Page 184: ...4 46 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II ConÞguration and Reset ...
Page 202: ...Part III vi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 266: ...8 34 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 382: ...10 106 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 392: ...11 10 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 430: ...Part IV viii MOTOROLA Part IV Communications Processor Module ...
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Page 980: ...A 4 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Appendixes ...
Page 1002: ...Index 22 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA INDEX ...
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