MPC8280 datasheet(1118/1386 Pages) FREESCALE

1118 / 1386 page

ATM AAL2

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

33-12

Freescale Semiconductor

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.

0x1C

0–1

—

Reserved, should be cleared during initialization.

2–7

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.

8–15

MaxStep

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.”

0x1E

0–1

—

Reserved, should be cleared during initialization.

2–7

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.

8–11

—

Reserved, should be cleared during initialization.

OneP

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.

STPT

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.

Performance monitoring

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.

Boldfaced entries must be initialized by the user.

Table 33-1. AAL2 Protocol-Specific Transmit Connection Table (TCT) Field Descriptions (continued)

Offset

Bits

Name1

Description

MPC8280 Datasheet(PDF) 1118 Page - Freescale Semiconductor, Inc

MPC8280 Datasheet(HTML) 1118 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL