DP83902A datasheet(18/70 Pages) NSC

18 / 70 page

70 Packet Reception (Continued)

6 Place the ST-NIC in either mode 1 or mode 2 loopback

This can be accomplished by setting bits D2 and D1 of

the Transmit Configuration Register to ‘‘01’’ or ‘‘10’’

respectively

7 Issue the START command to the ST-NIC This can be

accomplished by writing 22H to the Command Register

This is necessary to activate the ST-NIC’s Remote DMA

channel

8 Remove one or more packets from the receive buffer

ring

9 Reset the overwrite warning (OVW overflow) bit in the

Interrupt Status Register

10 Take the ST-NIC out of loopback This is done by writ-

ing the Transmit Configration Register with the value it

contains during normal operation (Bits D2 and D1

should both be programmed to 0)

11 If the ‘‘Resend’’ variable is set to a 1 reset the ‘‘Re-

send’’ variable and reissue the transmit command This

is done by writing a value of 26H to the Command Reg-

ister If the ‘‘Resend’’ variable is 0 nothing needs to be

done

Note 1

If Remote DMA is not being used the ST-NIC does not need to be

started before packets can be removed from the receive buffer ring Hence

step 8 could be done before step 7

Note 2

When the ST-NIC is in STOP mode the Missed Talley Counter is

disabled

Received Packet Aborted If It Hits Boundary

TLF11157 – 13

DP83902A 데이터시트(PDF) 18 Page - National Semiconductor (TI)