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MOTOROLA Chapter 6. Programming Model 6-23
PRELIMINARYÑSUBJECT TO CHANGE WITHOUT NOTICE
exact values depend on the application. The sequence resembles that shown in Table 6-27.
6.3.2.1 Descriptor Controller Initialization
In the FEC, the descriptor control machine initializes a few registers whenever
ECNTRL[ETHER_EN] is set. The transmit and receive FIFO pointers are reset, the
transmit backoff random number is initialized and the transmit and receive blocks are
activated. After the descriptor controller initialization sequence completes, hardware is
ready for operation, waiting for R_DES_ACTIVE and X_DES_ACTIVE to be asserted by
the user.
6.3.2.2 User Initialization (after Asserting ECNTRL[ETHER_EN])
The user must initialize portions of the FEC after setting ECNTRL[ETHER_EN]. The
exact values depend on the application. The sequence resembles that shown in Table 6-27
Table 6-27. User Initialization (before Setting ECNTRL[ETHER_EN])
Step Description
1 Set IMASK
2 Clear IEVENT
3 Set IVEC (deÞne ILEVEL)
4 Set R_FSTART (optional)
5 Set X_FSTART (optional)
6 Set ADDR_HIGH and ADDR_LOW
7 Set HASH_TABLE_HIGH and HASH_TABLE_LOW
8 Set R_BUFF_SIZE
9 Set R_DES_START
10 Set X_DES_START
11 Set R_CNTRL
12 Set X_CNTRL
13 Set FUN_CODE
14 Set MII_SPEED (optional)
15 Initialize (empty) TxBD ring
16 Initialize (empty) RxBD ring
17 Set Port D PDPAR register
18 Set Port D PDDIR register
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eescale S
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