Freescale Semiconductor MPC8260 - Manual (Page 1048)

ATM AAL1 Circuit Emulation Service
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
31-32 Freescale Semiconductor
Table 31-7. TCT Field Descriptions
Offset Bits Name Description
0x00 0–1 — Reserved, should be cleared during initialization.
2 GBL Global. Asserting GBL enables snooping of data buffers, BDs, interrupt queues and free
buffer pool.
3–4 BO Byte ordering. This field is used for data buffers.
00 Reserved.
01 Power PC little endian.
1x Big endian.
5 — Reserved, should be cleared during initialization.
6 DTB Data buffer and CES transmit cell scratchpad bus placement
0 Reside on the 60x bus.
1 Reside on the local bus.
Note: TCT[DTB] programming must be consistent across all CES transmit channels
because they share the same TCELL_TMP_BASE_EXT parameter.
7 BIB BD and interrupt queue bus
0 Reside on the 60xbus.
1 Reside on the local bus.
Note: When using AAL5, AAL1 or AAL1 CES in UDC mode, BDs and data should be
placed on the same bus (TCT[DTB]=TCT[BIB]).
8-9 — Reserved, should be cleared during initialization.
10-11 ATT ATM traffic type
00 Peak cell-rate pacing. The host must initialize PCR and the PCR fraction. Other
traffic parameters are not used.
01 Peak and sustain cell rate pacing (VBR traffic). The APC performs a
continuous-state leaky bucket algorithm (GCRA) to pace the channel-sustain cell
rate. The host must initialize PCR, PCR fraction, SCR, SCR fraction, and BT (burst
tolerance).
10 Peak and minimum cell rate pacing (UBR+ traffic). The host must initialize PCR, PCR
fraction, MCR, MCR fraction, and MDA.
11 Reserved.
12 AVCF Auto VC off. Determines APC behavior when the last buffer associated with this VC has
been sent and no more buffers are in the VC’s TxBD table,
0 The APC does not remove this VC from the schedule table and continues to schedule
it to transmit.
1 The APC removes this VC from the schedule table. To continue transmission after the
host adds buffers for transmission, a new ATM TRANSMIT command is needed, which
can be issued only after the CP clears the VCON bit. (Bit 13)
13 VCON Virtual channel is on
Should be set by the host before it issues an
ATM TRANSMIT command. When the host
sets TCT[STPS] (stop transmit), the CP deactivates this channel and clears VCON
when the channel is next encountered in the APC scheduling table. The host can issue
another
ATM TRANSMIT command only after the CP clears VCON.
14–15 INTQ Points to one of four interrupt queues available.