Freescale Semiconductor MPC8260 - Manual (Page 976)

ATM Controller and AAL0, AAL1, and AAL5
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
30-56 Freescale Semiconductor
Table 30-23 describes AAL1 protocol-specific TCT fields.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Offset + 0x10 — Valid Octet Size (VOS) PFM SRT SPF STF — SN
Offset + 0x12 SRTS_DEV Block Size
Offset + 0x14 SRTS_TMP Structured Pointer (SP)
Figure 30-32. AAL1 Protocol-Specific TCT
Table 30-23. AAL1 Protocol-Specific TCT Field Descriptions
Offset Bits Name Description
0x10 0-1 — Reserved, should be cleared.
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.
8 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.
9 SRT Synchronous residual time stamp. Unstructured format only. The PowerQUICC II
supports SRTS generation using external logic. If this mode is enabled, the
PowerQUICC II reads the SRTS from external logic and inserts it into four cells for which
SN = 1, 3, 5, or 7. The PowerQUICC II reads the new SRTS from external logic every
eight cells. (See
Section 30.15, “SRTS Generation and Clock Recovery Using External
Logic .”)
0 SRTS mode is not used.
1 SRTS mode is used.
10 SPF 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.
11 STF Structured format
0 Unstructured format is used.
1 Structured format is used.
12 — Reserved, should be cleared.
13–15 SN Sequence number field. Used by the CP to check the incoming cells SN. Should be
cleared initially.
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).
0x14 0–3 SRTS_TMP 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 SP Structured pointer. Used by the CP to calculate the structured pointer. Should be
cleared initially. Structured format only.