Motorola PowerQUICC II MPC8280 Series Reference Manual page 1051

• Automatic data forwarding. This mode enables automatic data forwarding between
AAL1/AAL0 and transparent mode over a TDM interface.
31.9.1 Automatic Data Forwarding
The basic concept of automatic data forwarding is to program the ATM controller and the
MCC to process the same BD table, as shown in Figure 31-21.
TDM Interface
UTOPIA Interface
UTOPIA Interface
TDM Interface
* The MCC and ATM receivers should be programmed to operate in opposite polarity E (empty) bit.
When going from TDM to ATM, the MCC receiver routes data from the TDM line to a
specific BD table. The ATM controller transmitter is programmed to operate on the same
table. When the MCC fills a receive buffer, the ATM controller sends it. The two controllers
synchronize on the MCC's RxBD[E] and the ATM controller's TxBD[R].
When going from ATM to TDM, the ATM receiver reassembles data received from a
particular channel to a specific BD table. The MCC transmitter is programmed to operate
on the same table. When the ATM controller fills a receive buffer, the MCC controller sends
it. The controllers synchronize on the ATM controller's RxBD[E] and the MCC's
TxBD[R].
The MCC and ATM receivers must be programmed to operate in opposite E-bit polarity.
That is, both receivers receive data into buffers whose RxBD[E] = 0 and set RxBD[E] when
a buffer is full. For the ATM receiver, set RCT[INVE] of the AAL1- and AAL0-specific
areas of the receive connection table; see Section 31.10.2.2, "Receive Connection Table
MOTOROLA Chapter 31. ATM Controller and AAL0, AAL1, and AAL5
Freescale Semiconductor, Inc.
MCC
Transmitter
MCC Tx ptr
ATM Rx ptr
ATM*
Receiver
ATM
Transmitter
ATM Tx ptr
MCC Rx ptr
MCC*
Receiver
Figure 31-21. ATM-to-TDM Interworking
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ATM-to-TDM Interworking
BD Table
Buffer 1
0 BD 1 Buffer 2
1 BD 2
Buffer 3
1 BD 3
0 BD 4
Buffer 4
0 BD 5
Buffer 5
BD Table
Buffer 1
0 BD 1 Buffer 2
1 BD 2
Buffer 3
1 BD 3
0 BD 4
Buffer 4
0 BD 5
Buffer 5
31-37