User manual

Inverse Multiplexing for ATM (IMA)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 33-31
33.4.4.1.1 IMA Group Transmit Control (IGTCNTL)
The fields of the IGTCNTL register are shown in Figure 33-14.
Table 33-6 describes the IGTCNTL bit fields.
1
Ensure transmit clock mode is not changed during IMA group startup to avoid erratic behavior.
33.4.4.1.2 IMA Group Transmit State (IGTSTATE)
The fields of the IGTSTATE register are shown in Figure 33-15.
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.
0 234567
Field — TXSC ISIE CTC ICPC
Figure 33-14. IMA Group Transmit Control (IGTCNTL)
Table 33-6. IGTCNTL Field Descriptions
Bits Name Description
0–2 — Reserved
3-4 TXSC Transmit status/control. Sets the transmit mode of the IMA group.
00 Filler mode. The IMA group transmits only ICP and filler cells, no data cells.
01 Active 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.
6CTC
1
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.
Table 33-5. IMA Group Transmit Table Entry (continued)
1
Offset Name Width Description