DP83936AVF datasheet(21/104 Pages) NSC

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30 Functional Description (Continued)

4 Program the Receive Control register with the desired re-

ceive filter and the loopback mode (LB1 LB0) In case of

transceiver loopback besides setting LB1 and LB0 to 1

the XWRAP bit in the DCR2 must also set to 1

5 Issue the transmit command (TXP) and enable the receiv-

er (RXEN) in the Command register

The SONIC-T completes the loopback operation after the

packet has been completely received (or rejected if there is

an address mismatch) The Transmit Control and Receive

Control registers treat the loopback packet as it would in

normal operation and indicate status accordingly Interrupts

are also generated if enabled in the Interrupt Mask register

Note

For MAC Loopback only one packet may be queued up for proper

operation This restriction occurs because the transmit MAC section

which does not generate an Interframe Gap (IFG) time between

transmitted packets does not allow the receive MAC section to up-

date receive status There are no restrictions for the other loopback

modes

39 NETWORK MANAGEMENT FUNCTIONS

The SONIC-T fully supports the Layer Management IEEE

8023 standard to allow a node to monitor the overall per-

formance of the network These statistics are available on a

per packet basis at the end of reception or transmission

In addition the SONIC-T provides three tally counters to

tabulate CRC errors Frame Alignment errors and missed

packets Table 3-1 shows the statistics indicated by the

SONIC-T

TLF12597 – 13

Note DSACK01 are used for both Bus and Slave Access Control and are bidirectional SMACK is used for both Slave access and shared memory access The

BMODE pin selects between NationalIntel or Motorola type busses

FIGURE 3-10 SONIC-T Bus Interface Signals

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