Motorola PowerQUICC II MPC8280 Series Reference Manual page 1181

Table 33-1. AAL2 Protocol-Specific Transmit Connection Table (TCT)
Offset Bits Name
0x1C 0–1
2–7
8–15 MaxStep
0x1E 0-1
2–7
8-11
12 OneP
13 STPT
14
15
1
Boldfaced entries must be initialized by the user.
33.3.5.2 CPS Tx Queue Descriptor
Each CPS TxBD table is managed by a CPS Tx queue descriptor (TxQD), as shown in
Figure 33-7. The TxQD contains the address of the next BD to be serviced, and other
queue-specific parameters. The NextQueue pointer is used to create a linked list of TxQDs,
as described in Section 33.3.2, "Transmit Priority Mechanism." The CPS TxQD is located
in the dual-port RAM, in a 16-byte aligned address.
MOTOROLA
Freescale Semiconductor, Inc.
Field Descriptions (continued)
1
— Reserved, should be cleared during initialization.
PMT Performance monitoring table. Points to one of the available 64
performance monitoring tables. The starting address of the table is
PMT_BASE+PMT*32.
Holds the number of TX Queues visited for each cell being prepared for
transmission. In fixed priority mode (TCT[Fix]=1), MaxStep should be set
to the total number of TX queues in the channel. See Section 33.3.2,
"Transmit Priority Mechanism."
— Reserved, should be cleared during initialization.
PFT Partial fill threshold. Used for partially filled cells only; see Section 33.3.3,
"Partial Fill Mode (PFM)." Specifies the maximum number of packet bytes
allowed in a CPS PDU. The range 1–48 are valid values.
If PFT=48 in partial fill mode, performance is adversely affected. When
not in partial fill mode, PFT must be initialized to 47.
— Reserved, should be cleared during initialization.
One packet per queue. See Section 33.3.2, "Transmit Priority
Mechanism."
0 The transmitter reads as many packets as possible from each TX queue
before moving to the next queue.
1 The transmitter reads only one packet from each TX queue before
advancing to the next queue.
Stop transmit. Should be cleared during initialization. When the host sets
this bit, the CP removes this channel from the APC and clears
TCT[VCON] flag.
Fix Fixed priority. See Section 33.3.2, "Transmit Priority Mechanism."
0 Round robin priority. The TX Queues related to this channel all share
the same priority.
1 Fixed priority. The TX Queues are ordered in a fixed priority ladder.
PM Performance monitoring
0 No performance monitoring for this VC.
1 Performance is monitored for this VC. When a cell is sent for this VC,
the performance monitoring table indicated in PMT field is updated.
Chapter 33. ATM AAL2
For More Information On This Product,
Go to: www.freescale.com
AAL2 Transmitter
Description
33-13