Freescale Semiconductor MPC8260 - Manual (Page 962)

ATM Controller and AAL0, AAL1, and AAL5
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
30-42 Freescale Semiconductor
a VC when sending a ATM TRANSMIT command, initiating the external CAM or address compression
tables, and when the CP sends an interrupt to an interrupt queue.
Example:
Suppose a configuration supports 1,024 regular ATM channels. To allocate 4 Kbytes of dual-port RAM
space to the internal connection table, determine that channel codes 0–63 are internal (64 VCs
× 64 bytes
(RCT and TCT) = 4 K). Channels 0–1 are reserved. The remaining 962 (1024 - 62) external channels are
assigned channel codes 256–1217. See
Figure 30-24 .
Figure 30-24. Example of a 1024-Entry Receive Connection Table
The general formula for determining the real starting address for all internal and external connection table
entries is as follows:
Connection table base address + (channel code
× 32)
Thus, the real starting address of the RCT entry associated with channel code 3 is as follows:
INT_RCT_BASE+ (3
× 32) = INT_RCT_BASE + 96
Even though it produces a gap in the connection table, the first external channel’s real starting address of
the RCT entry (channel code 256) is as follows:
EXT_RCT_BASE+ (256
× 32) = EXT_RCT_BASE + 8192
See Section 30.10.1, “Parameter RAM,” to find all the connection table base address parameters. (The
transmit connection table base address parameters are INT_TCT_BASE, EXT_TCT_BASE,
INT_TCTE_BASE, and EXT_TCTE_BASE.)
30.10.2.2 Receive Connection Table (RCT)
Figure 30-25 shows the format of an RCT entry.
Dual-Port RAM
INT_RCT_BASE
Reserved
RCT2
RCT3
RCT63
External Memory
EXT_RCT_BASE
RCT256
RCT257
RCT258
RCT259
RCT1217
Raw Cell (AAL0)