MPC8280 datasheet(1082/1386 Pages) FREESCALE

1082 / 1386 page

ATM AAL1 Circuit Emulation Service

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

32-22

Freescale Semiconductor

Figure 32-20. Pointer Verification Mechanism

32.8

AAL-1 Memory Structure

The CPM manages ATM traffic by means of transmit and receive buffer descriptors (BD) and by transmit

and receive connection tables (referred to as TCTs and RCTs, respectively). Buffer descriptors are circular

lists of pointers into transmit and receive buffer space in external memory. The following sections describe

the organization and configuration of the buffer descriptors, TCTs, and RCTs.

32.8.1

AAL1 CES Parameter RAM

The MPC8280 parameter RAM is used to configure the three FCCs. The CP also uses the parameter RAM

to store operational and temporary values. When configured for ATM mode, MPC8280 overlays the

configuration structures shown in the next tables. The following table includes fields for ATM operation

generally and AAL1 CES fields particularly.

Note that some of the values must be initialized by the user; values set by the CP should not be modified

by the user.

Table 32-3. AAL1 CES Field Descriptions

Offset

Name

Width

Description

0x00–

0x3F

—

Reserved, should be cleared during initialization.

0x40

RCELL_TMP_BASE

Hword

Rx cell temporary base address. Points to a total of 64 bytes reserved

dual-port RAM area used by the CP. Should be 64 byte aligned.

User-defined.

0x42

TCELL_TMP_BASE

Hword

Tx cell temporary base address. Points to total of 64 bytes reserved

dual-port RAM area used by the CP. Should be 64-byte aligned.

User-defined.

0x44

UDC_TMP_BASE

Hword

UDC mode only. Points to a total of 32 bytes reserved dual-port RAM

area used by the CP. Should be 64-byte aligned. User-defined.

Pointer mismatch/error

Missing pointer

Hunt mode

Pre-hunt mode

Sync mode

No pointer

Valid pointer

Pointer mismatch/error

Missing pointer

Valid pointer

new structured

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