Fast Ethernet Controllers (FEC0 and FEC1)
26-27
Freescale Semiconductor
26.4.22 Receive Descriptor Ring Start Registers (ERDSR0 & ERDSR1)
ERDSR
n
points to the start of the circular receive buffer descriptor queue in external memory. This pointer
must be 32-bit aligned; however, it is recommended it be made 128-bit aligned (evenly divisible by 16).
This register is not reset and must be initialized prior to operation.
26.4.23 Transmit Buffer Descriptor Ring Start Registers (ETSDR0 &
ETSDR1)
ETSDR
n
provides a pointer to the start of the circular transmit buffer descriptor queue in external memory.
This pointer must be 32-bit aligned; however, it is recommended it be made 128-bit aligned (evenly
Address: 0xFC03_0150 (FRSR0)
0xFC03_4150 (FRSR1)
Access: User read/write
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
R 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
R_FSTART
0
0
W
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0
0
0
Figure 26-21. FIFO Receive Start Register (FRSR
n
)
Table 26-25. FRSR
n
Field Descriptions
Field
Description
31–11
Reserved, must be cleared.
10
Reserved, must be set.
9–2
R_FSTART
Address of first receive FIFO location. Acts as delimiter between receive and transmit FIFOs. For proper
operation, ensure that R_FSTART is set to 0x48 or greater.
1–0
Reserved, must be cleared.
Address: 0xFC03_0180 (ERDSR0)
0xFC03_4180 (ERDSR1)
Access: User read/write
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
R
R_DES_START
0
0
W
Reset — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —
Figure 26-22. Ethernet Receive Descriptor Ring Start Register (ERDSR
n
)
Table 26-26. ERDSR
n
Field Descriptions
Field
Description
31–2
R_DES_START
Pointer to start of receive buffer descriptor queue.
1–0
Reserved, must be cleared.
Содержание MCF54455
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