MPC8280 datasheet(1095/1386 Pages) FREESCALE

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ATM AAL1 Circuit Emulation Service

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

32-35

Table 32-8. AAL1 CES Protocol-Specific TCT Field Descriptions

Offset

Bits

Name

Description

0x10

0–1

—

Reserved, should be cleared during initialization.

2–7

VOS

Valid octet size. Partially filled cell mode only. Specifies the number of valid octets from

the beginning of the AAL1 user data field. For unstructured service, values 1-47 are

valid; for structured service, values 1-46 are valid.

PFM

Partially filled mode.

0 Partially filled cells mode is not used.

1 Partially filled cells mode is used. The transmitter copies only valid octets from the

buffer to the AAL1 cell. The size of the valid octets from the beginning of the AAL1

user data field is specified in the VOS (valid octet size) field.

SRT

Synchronous residual time stamp. Unstructured format only. The MPC8280 supports

SRTS generation using external logic. If this mode is enabled, the MPC8280 reads the

SRTS from external logic and inserts it into four cells for which SN = 1, 3, 5, or 7. The

MPC8280 reads the new SRTS from external logic every eight cells. (See Section , “.”)

0 SRTS mode is not used.

1 SRTS mode is used.

SPIF

Structured pointer inserted flag. Indicates that a structured pointer has been inserted

in the current cycle. The user should initialize this field to zero. Used by the CP only.

STF

Structured format.

0 Unstructured format is used.

1 Structured format is used.

Note that although the structured format may be used, if the block size is one, the user

should clear STF so that only non P-format AAL1 cells are generated.

—

Reserved, should be cleared during initialization.

13–15

Sequence number field. Used by the CP to check the incoming cells SN. Initialize to 0.

0x12

0–3

SRTS_DEV

Used to select a SRTS device. The SRTS device address is

SRTS_BASE[0–27]+SRTS_DEV[28:31]. SRTS_BASE is taken from the parameter

RAM and is 16-byte aligned.

4–15

Block Size

Used only in structured format. Specifies the structured block size (Block Size = 0xFFF

= 4 Kbytes maximum).

Note that when working in CAS mode (CESM=1 and CASM=1), the block size should

be programmed to the superframe block size plus the size of the CAS block. However,

when working in basic mode (CES without CAS: CESM=1 and CASM=0) the block size

should be programmed to the number of MCC slots (Nx64) per frame assigned to this

channel.

0x14

0–3

ICASB/SRTS

_TMP

ICASB applies when in CAS mode. Incoming CAS Block. Points to one of the eight

available internal CAS block. The starting address of the table is

IN_CAS_BLOCK_BASE+ICASB

× 32. See Section 32.4.7.1, “CAS Routing Table” for

more details.

Note that the RCT and TCT use the same CAS routing table (CRT).

SRTS_TMP applies when not in CAS mode. Before a cell with SN = 1 is sent, the CP

reads the SRTS code from external SRTS logic, writes it to SRTS_TMP, and then

inserts SRTS_TMP into the next four cells with an odd SN.

4–15

Structured pointer. Used by the CP to calculate the structured pointer. Initialize to 0.

Structured format only.

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