Freescale Semiconductor MPC8250, Family Reference Manual

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ATM AAL2
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
32-28 Freescale Semiconductor
32.4.4.4 CPS Receive Buffer Descriptor (RxBD)
The CPS RxBD structure consists of a BD table that points to data buffers. The RxBDs contain, apart from
the buffer pointer, the packet header, as shown in
Figure 32-17 . The buffers contain the packet payload.
Table 32-8 describes the CPS RxBD fields.
Table 32-7. CPS RxQD Field Descriptions
Offset Bits Name
1
1
Boldfaced entries must be initialized by the user.
Description
0x00 0–11 — Reserved, should be cleared during initialization.
12 RBM Receive buffer mask.
0 Disable receive buffer interrupt.
1 Enable receive buffer interrupt.
13 — Reserved, should be cleared during initialization.
14-15 SubType SubType. Sublayer type, should be 00 (CPS) for this descriptor.
00 CPS sublayer.
01 CPS switched.
10 SSSAR.
11 Reserved.
0x02 — RxBD Table
Offset Holds the offset to the next BD to be opened by the receiver. Should be cleared
during initialization.
0x04 — RxBD Table
Base Holds the pointer to the first BD in the BD table.
0 1 2 3 4 6 7 8 15
0x00 E CM W I — UP CPS Packet Header
0x02 Packet Header
0x04 Rx Data Buffer Pointer (RXDBPTR)
0x06
Figure 32-17. CPS Receive Buffer Descriptor