Freescale Semiconductor MPC860T user manual Descriptor Controller Initialization, Step Description

Models: MPC860T

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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

 

 

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

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Freescale Semiconductor MPC860T Descriptor Controller Initialization, User Initialization after Asserting Ecntrletheren