MPC8280 datasheet(1171/1386 Pages) FREESCALE

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Inverse Multiplexing for ATM (IMA)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

34-25

34.4.3.1

IMA Control (IMACNTL)

The fields of the IMACNTL are shown in Figure 34-13.

Table 34-4 describes the IMACNTL bit fields.

34.4.4

IMA Group Tables

The IMA group tables consist of multiple IMA group structures indexed by group number, which ranges

from 0 to 7. The transmit and receive parameters are located in separate tables. The IMA group transmit

table entries are 16 bytes long. The IMA group receive table entries are 64 bytes long. However, there is

no need to reserve memory space in DPRAM for 8 receive IMA groups if less than 8 IMA groups are

required. To conserve memory space used by these tables, it is best to add groups starting from group

zero. Note also that group number is independent of the assignment of IMA ID.

34.4.4.1

IMA Group Transmit Table Entry

01234567

Field

—

IRSE

IQB

DSB

—

INTQ

Figure 34-13. IMA Control (IMACNTL)

Table 34-4. IMACNTL Field Descriptions

Bits

Name

Description

0–1

—

Reserved

IRSE

IMA link receive statistics enable. If link receive statistics gathering is disabled, there is no

need to initialize IRLINKSTAT or reserve space for the receive statistics table.

Link receive statistics gathering is disabled.

Link receive statistics gathering is enabled.

IQB

Interrupt queue bus. Defines on which bus the IMA interrupt queue is located.

On the 60x bus.

On the local bus.

DSB

Data structure bus. Defines on which bus the IMA external structure memory area is

located.

On the 60x bus.

On the local bus.

—

Reserved.

6–7

INTQ

Number of the ATM interrupt queue dedicated to IMA events. Note that these do not include

ICP cell reception events; the handling of ICP cell reception events is programmed in the

RCT of the ICP channel defined by RICPCH.

Table 34-5. IMA Group Transmit Table Entry 1

Offset

Name

Width

Description

0x00

IGTCNTL

Byte

IMA group transmit control parameters.

0x01

IGTSTATE

Byte

IMA group transmit state. Microcode-managed parameter. Must be

initialized to zero at group start-up.

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