MPC8280 datasheet(1077/1386 Pages) FREESCALE

1077 / 1386 page

ATM AAL1 Circuit Emulation Service

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

32-17

Table 32-2 describes CES adaptive threshold table fields.

Offset + 0x00

—

CES Adaptive Counter

Offset + 0x02

ATM Stop Threshold

ATM Start Threshold

Offset + 0x04

MCC Stop Threshold

MCC Start Threshold

Offset + 0x06

—

Figure 32-15. CES Adaptive Threshold Table

Table 32-2. CES Adaptive Threshold Table Field Descriptions

Offset1

1 The offset is CATB + RCT[Super_Channel_Number]# × 8

Bits

Name

Description

0x00

0–7

—

Reserved, should be cleared during initialization.

8–15 CESAC CES adaptive counter.This field contains the difference between the ATM write pointer and

the MCC read pointer on the common BD table.This field should be cleared by the user

during the channel initialization.

0x02

0–7

ASTP

ATM stop threshold.This threshold determines the maximum amount of buffering (CDVT)

that required in the common BD table (shown in Figure 32-16). When the CESAC reaches

this value a pre-overrun condition occurs.This field should be defined by the user during the

channel initialization.

8–15

ASTRT ATM start threshold.This threshold determines the Time interval that will take the ATM

controller to restart the synchronize process (shown in Figure 32-16) after pre-overrun

condition.This field should be defined by the user during the channel initialization.

0x04

0–7

MSTP

MCC stop threshold.This threshold determines the minimum amount of buffering in the

common BD table (shown in Figure 32-16).When the CESAC reaches this value a

pre-underrun condition occur and the MCC starts to transmit the underrun template or the

last BD (see Section 32.5, “ATM-to-TDM Adaptive Slip Control”).This field should be defined

by the user during the channel initialization.

8–15 MSTRT MCC start threshold.This threshold determines the effective depth of the jitter buffer, the

amount of buffering required to cope with the ATM network’s CDV (shown in

Figure 32-16).When the CESAC reaches this value the MCC transmitter starts sending the

valid data from the common BD table.This field should be defined by the user during the

channel initialization.

0x06

0–15

—

Reserved, should be cleared during initialization.

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