Motorola PowerQUICC II MPC8280 Series Reference Manual page 1073

31.10.2.3.2 AAL1 Protocol-Specific TCT
Figure 31-32 shows the AAL1 protocol-specific TCT.
0 1
Offset + 0x10 —
Offset + 0x12 SRTS_DEV
Offset + 0x14 SRTS_TMP
Table 31-23 describes AAL1 protocol-specific TCT fields.
Table 31-23. AAL1 Protocol-Specific TCT Field Descriptions
Offset Bits Name
0x10 0-1 —
2–7 VOS
8 PFM
9 SRT
10 SPF
11 STF
12 —
13–15 SN
0x12 0–3 SRTS_DEV Used to select a SRTS device. The SRTS device address is
4–15 Block Size Used only in structured format. Specifies the structured block size (Block Size
MOTOROLA Chapter 31. ATM Controller and AAL0, AAL1, and AAL5
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2 3 4 5 6
Valid Octet Size (VOS)
Figure 31-32. AAL1 Protocol-Specific TCT
Reserved, should be cleared.
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.
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.
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 31.16,
"SRTS Generation and Clock Recovery Using External Logic.")
0 SRTS mode is not used.
1 SRTS mode is used.
Structured pointer flag. Indicates that a structured pointer has been inserted in the
current block. The user should initialize this field to zero. Used by the CP only.
Structured format
0 Unstructured format is used.
1 Structured format is used.
Reserved, should be cleared.
Sequence number field. Used by the CP to check the incoming cells SN. Should be
cleared initially.
SRTS_BASE[0–27]+SRTS_DEV[28:31]. SRTS_BASE is taken from the parameter
RAM and is 16-byte aligned.
= 0xFFF = 4 Kbytes maximum).
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ATM Memory Structure
7 8 9 10 11
PFM SRT SPF STF
Block Size
Structured Pointer (SP)
Description
12 13 14 15
— SN
31-59