MPC8280 datasheet(1011/1386 Pages) FREESCALE

1011 / 1386 page

ATM Controller and AAL0, AAL1, and AAL5

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

31-51

Table 31-21 describes general TCT fields.

Table 31-21. TCT Field Descriptions

Offset

Bits

Name

Description

0x00

0–1

—

Reserved, should be cleared.

GBL

Global. Asserting GBL enables snooping of data buffers, BDs, interrupt queues and free

buffer pool.

3–4

Byte ordering. This field is used for data buffers.

00 Reserved

01 Power PC little endian

1x Big endian

—

Reserved, should be cleared.

DTB

Data buffer bus

0 Reside on the 60x bus.

1 Reside on the local bus.

BIB

BD, interrupt queue and external SRTS logic bus

0 Reside on the 60xbus.

1 Reside on the local bus.

Note: When using AAL5, AAL1 CES in UDC mode, BDs and data should be placed on

the same bus (TCT[DTB]=TCT[BIB]).

AVCF

Auto VC off. Determines the behavior of the APC when the last buffer associated with

this VC has been sent and no more ready buffers are in the VC’s TxBD table.

0 The APC does not remove this VC from the schedule table and continues to schedule

it to transmit.

1 The APC removes this VC from the schedule table. To continue transmission after the

host adds buffers for transmission, a new ATM TRANSMIT command is needed, which

can be issued only after the CP clears TCT[VCON].

Note: When over-subscribing UBR or UBR+ channels, set AVCF so that the CPM does

not become overloaded polling non-active VCs.

—

Reserved, should be cleared.

10–11

ATT

ATM traffic type

00 Peak cell-rate pacing. The host must initialize PCR and the PCR fraction. Other

traffic parameters are not used.

01 Peak and sustain cell rate pacing (VBR traffic). The APC performs a

continuous-state leaky bucket algorithm (GCRA) to pace the channel-sustain cell

rate. The host must initialize PCR, PCR fraction, SCR, SCR fraction, and BT (burst

tolerance).

10 Peak and minimum cell rate pacing (UBR+ traffic). The host must initialize PCR,

PCR fraction, MCR, MCR fraction, and MDA.

11 Reserved

CPUU

CPCS-UU+CPI insertion (used for AAL5 only).

0 CPCS-UU+CPI insertion disabled. The transmitter clears the CPCS-UU+CPI fields.

1 CPCS-UU+CPI insertion enabled. The transmitter reads the CPCS-UU+CPI (16-bit

entry) from external memory. It should be placed after the end of the last buffer (it

should not be included in the buffer length).

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