E t h e r n e t M o d u l e

 

 

 

 

 

 

 

 

 

 

Bits

Access

Mnemonic

Reset

Description

 

 

 

 

 

D19

R/W

ETXREG

0

Enable Transmit Data register ready interrupt

 

 

 

 

Set to 1 to generate an interrupt when the TX FIFO

 

 

 

 

is ready to accept data.

 

 

 

 

 

D18

R/W

ETFIFOH

0

Enable transmit data FIFO half empty interrupt

 

 

 

 

Must be set to 1 to generate an interrupt when the

 

 

 

 

TX FIFO is at least half empty (<256 bytes).

 

 

 

 

 

D17

R/W

ETXBC

0

Enable transmit buffer complete interrupt

 

 

 

 

Set to 1 to generate an interrupt when the transmit

 

 

 

 

packet transmission is complete.

 

 

 

 

 

D16

R/W

EFULLD

0

Enable full-duplex operation

 

 

 

 

Set to 1 to allow the Ethernet TX and RX DMA

 

 

 

 

operations to operate simultaneously. This bit must

 

 

 

 

be set when the Ethernet link negotiation results in

 

 

 

 

full-duplex mode.

 

 

 

 

It is recommended that you limit transmit frames to

 

 

 

 

512 bytes when full-duplex operation is enabled.

 

 

 

 

 

D15:14

R/W

MODE

0

Ethernet interface mode

 

 

 

 

00 10/100 Mbps MII mode

 

 

 

 

10 10 Mbps Level 1 ENDEC mode

 

 

 

 

11 10 Mbps SEEQ ENDEC mode

 

 

 

 

Identifies the type of Ethernet PHY attached to the

 

 

 

 

NS7520.

 

 

 

 

In ENDEC SEEQ mode, the LPBK pin is inverted

 

 

 

 

before driving the MDC pin.

 

 

 

 

In ENDEC Level 1 mode, the PDN signal is driven

 

 

 

 

using an open-drain output driver.

 

 

 

 

 

D13

N/A

Reserved

N/A

Reads as zero.

 

 

 

 

 

D12

R/W

RXCINV

0

Invert the receive clock input

 

 

 

 

Set to 1 only when the external Ethernet PHY

 

 

 

 

generates a clock that is inverted in phase relative

 

 

 

 

to what the MAC is expecting.

This bit is not required for most commercially available PHY devices.

Table 53: Ethernet General Control register bit definition

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Digi NS7520 manual Enable Transmit Data register ready interrupt, Enable transmit data Fifo half empty interrupt