Motorola PowerQUICC II MPC8280 Series Reference Manual page 1239

Table 34-5. IMA Group Transmit Table Entry (continued)
Offset Name
0x0C TNUMLINKS
0x0D RTSTPCNT
0x0E IASNCCtr
0x0F IASNC
1
Boldfaced entries must be initialized by the user. All other parameters initialize to zero.
34.4.4.1.1 IMA Group Transmit Control (IGTCNTL)
The fields of the IGTCNTL register are shown in Figure 34-14.
0
Field
Figure 34-14. IMA Group Transmit Control (IGTCNTL)
Table 34-6 describes the IGTCNTL bit fields.
Bits Name
0–2 — Reserved
3-4 TXSC Transmit status/control. Sets the transmit mode of the IMA group.
00Filler mode. The IMA group transmits only ICP and filler cells, no data cells.
01Active mode. The IMA group is capable of sending data cells.
1XReserved.
5 ISIE Required for optional TRL Service Latency enhancement only.
IMA Scheduler Split Iterations Enable
0 - APC is not split, TRL completes round robin distribution of cells.
1 - APC split, both TRL and non-TRL requests distribute cells to the transmit queues.
1
6 CTC Transmit clock mode for this IMA group.
0 Independent transmit clock (ITC) mode.
1 Common transmit clock (CTC) mode.
7 ICPC ICP change flag. Maintains at least the minimum 2-frame spacing of ICP cell control/status
changes. Initialize to zero at group start-up.
Must be toggled by software whenever TICPPTR is changed.
After two subsequent IMA frames are transmitted, the IGTSTATE[ICPCA] field will be changed
to match IGTCNTL[ICPC]. When IGTCNTL[ICPC] equals IGTSTATE[ICPCA], changes to
TICPPTR are allowed.
1
Ensure transmit clock mode is not changed during IMA group startup to avoid erratic behavior.
MOTOROLA
Freescale Semiconductor, Inc.
Width
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.
Byte Real time-stamp subcounter. Microcode-managed parameter, used by the
APC. Initialize to zero at group start-up.
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.
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.
2
—
Table 34-6. IGTCNTL Field Descriptions
Chapter 34. Inverse Multiplexing for ATM (IMA)
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IMA Programming Model
Description
3 4 5
TXSC ISIE
Description
1
6 7
CTC ICPC
34-29