Motorola MPC8260 - Manual (Page 833)

29-53 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
0x02 0 Ñ Internal use only. Initialize to 0.
1 INF Used for AAL5 Only. Indicates the transmitter state. Initialize to 0
0 In idle state.
1 In AAL5 frame transmission state.
2Р11 С Internal use only. Initialize to 0.
12 ABRF Used for AAL5 Only.
0 ABR Flow control is disabled.
1 ABR Flow control is enabled.
13Ð15 AAL AAL type
000 AAL0ÑSegmentation without any adaptation layer.
001 AAL1ÑATM adaptation layer 1 protocol.
010 AAL5ÑATM adaptation layer 5 protocol.
0x04 Ñ TxDBPTR Tx data buffer pointer. Holds the real address of the current position in the Tx buffer.
0x08 Ñ TBDCNT Transmit BD count. Counts the remaining data to transmit in the current transmit buffer.
Its initial value is loaded from the data length Þeld of the TxBD when a new buffer is
open; its value is subtracted for any transmitted cell associated with this channel.
0x0A Ñ TBD_OffSet Transmit BD offset. Holds offset from TBD_BASE of the current BD. Initialize to 0.
0x0C 0Ð7 Rate
Reminder
Rate remainder. Used by the APC to hold the rate remainder after adding the pace
fraction to the additive channel rate. Initialize to 0.
8Ð15 PCR Fraction Peak cell rate fraction. Holds the peak cell rate fraction of this channel in units of 1/256
slot. If this is an ABR channel, this Þeld is automatically updated by the CP.
0x0E Ñ PCR Peak cell rate. Holds the peak cell rate (in units of APC slots) permitted for this channel
according to the trafÞc contract. Note that for an ABR channel, the CP automatically
updates PCR to the ACR value.
0x10 С С Protocol-speciÞc
0x16 Ñ APCLC APC linked channel. Used by the CP. Initialize to 0 (null pointer).
0x18 Ñ ATMCH ATM cell header. Holds the full (4-byte) ATM cell header of the current channel. The
transmitter appends ATMCH to the cell payload during transmission.
0x1C 0Р1 С Reserved, should be cleared.
2Ð7 PMT Performance monitoring table. Points to one of the available 64 performance
monitoring tables. The starting address of the table is PMT_BASE+PMT
´ 32. Can be
changed on-the-Яy.
8Р15 TBD_BASE TxBD base. Points to the Þrst BD in the channelÕs TxBD table. The 8 most-signiÞcant
bits of the address are taken from BD_BASE_EXT in the parameter RAM. The four
least-signiÞcant bits of the address are taken as zero.
0x1E 0Ð11
12 BNM Buffer-not-ready interrupt mask. Can be changed on-the-ßy.
0 The transmit buffer-not-ready event of this channel is masked. (TBNR event is not
sent to the interrupt queue.)
1 The buffer-not-ready event of this channel is enabled.
13 STPT Stop transmit. Initialize to 0. When the host sets this bit, the CP deactivates this
channel and clears TCT[VCON] when the channel is next encountered in the APC
scheduling table. Note that for AAL5 if STPT is set and frame transmission is already
started (TCT[INF]=1), an abort indication will be sent (last cell with zero length Þeld).
Table 29-21. TCT Field Descriptions (Continued)
Offset Bits Name Description