MPC8280 datasheet(1012/1386 Pages) FREESCALE

1012 / 1386 page

ATM Controller and AAL0, AAL1, and AAL5

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

31-52

Freescale Semiconductor

VCON

Virtual channel is on.

Should be set by the host before it issues an ATM TRANSMIT command. When the host

sets TCT[STPT] (stop transmit), the CP deactivates this channel and clears VCON

when the channel is next encountered in the APC scheduling table. The host can issue

another ATM TRANSMIT command only after the CP clears VCON.

14–15

INTQ

Points to one of four interrupt queues available.

0x02

—

Internal use only. Should be cleared.

INF

Used for AAL5 Only. Indicates the transmitter state. Initialize to 0

0 In idle state.

1 In AAL5 frame transmission state.

2–11

—

Internal use only. Should be cleared.

ABRF

Used for AAL5 Only.

0 ABR Flow control is disabled.

1 ABR Flow control is enabled.

13–15

AAL

AAL type

000 AAL0—Reassembly with no adaptation layer

001 AAL1—ATM adaptation layer 1 protocol

010 AAL5—ATM adaptation layer 5 protocol

100 AAL2—ATM adaptation layer 2 protocol. Refer to Chapter 33, “ATM AAL2.”

101 AAL1_CES—Refer to Chapter 32, “ATM AAL1 Circuit Emulation Service.”

All others reserved.

0x04

—

TxDBPTR

Tx data buffer pointer. Holds the real address of the current position in the Tx buffer.

0x08

—

TBDCNT

Transmit BD count. Counts the remaining data to transmit in the current transmit buffer.

Its initial value is loaded from the data length field of the TxBD when a new buffer is

open; its value is subtracted for any transmitted cell associated with this channel.

0x0A

—

TBD_OffSe

Transmit BD offset. Holds offset from TBD_BASE of the current BD. Should be cleared

initially.

0x0C

0–7

Rate

Reminder

Rate remainder. Used by the APC to hold the rate remainder after adding the pace

fraction to the additive channel rate. Should be cleared initially.

8–15

PCR

Fraction

Peak cell rate fraction. Holds the peak cell rate fraction of this channel in units of 1/256

slot. If this is an ABR channel, this field is automatically updated by the CP.

0x0E

—

PCR

Peak cell rate. Holds the peak cell rate (in units of APC slots) permitted for this channel

according to the traffic contract. Note that for an ABR channel, the CP automatically

updates PCR to the ACR value.

0x10

—

Protocol-specific

0x16

—

APCLC

APC linked channel. Used by the CP. Initialize to 0 (null pointer).

0x18

—

ATMCH

ATM cell header. Holds the full (4-byte) ATM cell header of the current channel. The

transmitter appends ATMCH to the cell payload during transmission.

Table 31-21. TCT Field Descriptions (continued)

Offset

Bits

Name

Description

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