AX88796ALF datasheet(34/68 Pages) ASIX

34 / 68 page

AX88796ALF

3-in-1 Local Bus Fast Ethernet Controller

4.2.5

Other Useful Operations

MEMORY DIAGNOSTICS

Memory diagnostics can be achieved by Remote Write/Read DMA operations. The following is a suggested

step for memory test and assume the AX88796A has been well initialized.

1. Issue the STOP command to the AX88796A. This is accomplished be setting the STP bit in the

AX88796A’s Command Register. Writing 21H to the Command Register will stop the AX88796A.

2. Wait for at least 1.5 ms. Since the AX88796A will complete any reception that is in progress, it is necessary

to time out for the maximum possible duration of an Ethernet reception. This action prevents buffer

memory from written data through Local DMA Write.

3. Write data pattern to MUT (memory under test) by Remote DMA write operation.

4. Read data pattern from MUT (memory under test) by Remote DMA read operation.

5. Compare the read data pattern with original write data pattern and check if it is equal.

6. Repeat step 3 to step 5 with various data pattern.

LOOPBACK DIAGNOSTICS

1. Issue the STOP command to the AX88796A. This is accomplished be setting the STP bit in the

AX88796A’s Command Register. Writing 21H to the Command Register will stop the AX88796A.

2. Wait for at least 1.5 ms. Since the AX88796A will complete any reception that is in progress, it is necessary

to time out for the maximum possible duration of an Ethernet reception. This action prevents buffer

memory from written data through Local DMA Write.

3. Place the AX88796A in mode 1 loop back. (MAC internal loop back) This can be accomplished by setting

bits D2 and D1, of the Transmit Configuration Register to ``0,1’’.

4. Issue the START command to the AX88796A. This can be accomplished by writing 22H to the Command

5. Write data that want to transmit to transmit buffer by Remote DMA write operation.

6. Issue the TXP command to the AX88796A. This can be accomplished by writing 26H to the Command

7. Read data current receive buffer by Remote DMA read operation.

8. Compare the received data with original transmit data and check if it is equal.

9. Repeat step 5 to step 8 for more packets test.

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