MPC8280 datasheet(1172/1386 Pages) FREESCALE

1172 / 1386 page

Inverse Multiplexing for ATM (IMA)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

34-26

Freescale Semiconductor

0x02

TGRPORDER

Hword

Offset of transmit group order table in DPRAM. Can be changed on the fly.

0x04

TVPHYNUM

Byte

Transmit Virtual PHY number. Maps this IMA transmit group to a virtual

PHY number for the purpose of selecting an ATM pace controller (APC)

table number for this IMA group. Note that this parameter must be unique;

it must not conflict with the PHY number of any non-IMA PHYs or with the

TVPHYNUM of any other IMA group.

If there are any PHY numbers which will never be used in a system (i.e. the

actual PHY with the address does not exist), then TVPHYNUM should be

selected from one of these PHYs. If no such PHY numbers are available

(i.e. the multi-PHY interface consists of the full 31 PHYs), then select

TVPHYNUM from one of the PHY numbers of the PHYs within this IMA

group.

0x05

TIFSN

Byte

Transmit IMA Frame Sequence Number (IFSN). Microcode-managed

parameter. Increments each time an IMA frame is transmitted, cycling from

0 through 255. Should be initialized to zero at group start-up.

0x06

TMCTR

Byte

Transmit IMA M counter. Microcode-managed parameter. Tracks IMA frame

boundaries. Increments once per round-robin distribution of cells to the

transmit queues, cycling from 0 through M. Initialize to zero at group startup.

0x07

TRLSTFCNT

Byte

TRL stuff frame counter. Microcode-managed parameter. Controls required

stuffing on the TRL. Decrements each time an ICP cell is sent on the TRL,

cycling from TRLSTFN through 0. A TRL stuff event occurs when it reaches

zero. Initialize to the value of TRLSTFN at group start-up.

0x08

TICPPTR

Hword

Offset of transmit ICP cell payload template area in DPRAM. Must be

64-byte aligned. This parameter and the associated template area may only

be changed when IGCNTL[ICPC]=IGTSTATE[ICPCA].

After changing TICPPTR, IGCNTL[ICPC] must be toggled.

0x0A

Byte

Transmit IMA frame size. Program to 31, 63, 127, or 255 for frame sizes (M)

of 32, 64, 128, or 256, respectively.

0x0B

TRLSTFN

Byte

TRL stuff frame number. Defines the number of IMA frames sent between

TRL stuff events.

For ITC operation IGTCNT[CTC] = 0, program TRLSTFN = 2048/M. For

CTC operation IGTCNT[CTC] = 1, program TRLSTFN = (2048/M) – 1.

Refer to Section 34.4.4.1.1, “IMA Group Transmit Control (IGTCNTL)."

0x0C

TNUMLINKS

Byte

Number of transmit links in the IMA group that are in the active state

(ILTCNTL[TXSC]=01). Used by the APC to scale the rescheduling

parameters appropriately when rescheduling channels.

0x0D

RTSTPCNT

Byte

Real time-stamp subcounter. Microcode-managed parameter, used by the

APC. Initialize to zero at group start-up.

0x0E

IASNCCtr

Byte

Required for optional TRL Service Latency enhancement only.

IMA APC Scheduled Number of Cells Counter - Number of cells passed to

the groups links upon request. Initialize to IASNC.

0x0F

IASNC

Byte

Required for optional TRL Service Latency enhancement only.

IMA APC Scheduled Number of Cells - reset for IASNCtr. Number of cells

passed to the groups links upon request. Recommended value is 1.

1 Boldfaced entries must be initialized by the user. All other parameters initialize to zero.

Table 34-5. IMA Group Transmit Table Entry (continued)1

Offset

Name

Width

Description

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