DP83916 datasheet(68/96 Pages) NSC

68 / 96 page

50 Bus Interface (Continued)

13 PCOMP will not be asserted (DCR2)

14 Packets will be accepted (not rejected) on CAM match

(DCR2)

A software reset immediately terminates DMA operations

and future interrupts The chip is put into an idle state where

registers can be accessed but the SONIC-16 will not be

active in any other way The registers are affected by a

software reset as shown in Table 5-4 (only the Command

60 Network Interfacing

The SONIC-16 contains an on-chip ENDEC that performs

the network interfacing between the AUI (Attachment Unit

Interface) and the SONIC-16’s MAC unit A pin selectable

option allows the internal ENDEC to be disabled and the

MACENDEC signals to be supplied to the user for connec-

tion to an external ENDEC If the EXT pin is tied to ground

(EXTe0) the internal ENDEC is selected and if EXT is tied

to VCC (EXTe1) the external ENDEC option is selected

Internal ENDEC

When the internal ENDEC is used

(EXTe0) the interface signals between the ENDEC and

MAC unit are internally connected While these signals are

used internally by the SONIC-16 they are also provided as

an output to the user

(Figure 6-1)

The internal ENDEC allows for a 2-chip solution for the

complete Ethernet interface

Figure 6-2 shows a typical dia-

gram of the network interface

TLF11722 – 52

FIGURE 6-1 MAC and Internal ENDEC Interface Signals

DP83916 Datasheet(PDF) 68 Page - National Semiconductor (TI)