DP83907 datasheet(30/70 Pages) NSC

30 / 70 page

50 Register Descriptions (Continued)

COMMAND REGISTER (CR)

00H (READWRITE)

The Command Register is used to initiate transmissions enable or disable Remote DMA operations and to select register

pages To issue a command the microprocessor sets the corresponding bit(s) (RD2 RD1 RD0 TXP) Further commands may

be overlapped but with the following rules (1) If a transmit command overlaps with a remote DMA operation bits RD0 RD1

and RD2 must be maintained for the remote DMA command when setting the TXP bit Note if a remote DMA command is re-is-

sued when giving the transmit command the DMA will complete immediately if the remote byte count register has not been re-

initialized (2) If a remote DMA operation overlaps a transmission RD0 RD1 and RD2 may be written with the desired values

and a ‘‘0’’ written to the TXP bit Writing a ‘‘0’’ to this bit has no effect (3) A remote write DMA may not overlap remote read

operation or vice versa Either of these operations must either complete or be aborted before the other operation may start Bits

PS1 PS0 RD2 and STP may be set any time

PS1

PS0

RD2

RD1

RD0

TXP

STA

STP

Bit

Symbol

Description

STP

STOP

Software reset command takes the controller off-line no packets will be received or transmitted

Any reception or transmission in progress will continue to completion before entering the reset state To

exit this state the STP bit must be reset and the STA bit must be set high To perform a software reset

this bit should be set high The software reset has executed only when indicated by the RST bit in the

ISR being set to 1 STP powers up high

Note

If the DP83907 has previously been in start mode and the STP is set both the STP and STA bits will remain set

STA

START

This bit is used to activate the NIC Core after either power up or when the NIC Core has been

placed in a reset mode by software command or error STA powers up low

TXP

TRANSMIT PACKET

This bit must be set to initiate transmission of a packet TXP is internally reset

either after the transmission is completed or aborted This bit should be set only after the Transmit Byte

Count and Transmit Page Start registers have been programmed

D3 – D5

RD0 – RD2

REMOTE DMA COMMAND

These three encoded bits control operation of the Remote DMA channel

RD2 can be set to abort any Remote DMA command in progress The Remote Byte Count Registers

should be cleared when a Remote DMA has been aborted The Remote Start Addresses are not

restored to the starting address if the Remote DMA is aborted

RD2

RD1

RD0

Not Allowed

Remote Read

Remote Write (Note 2)

Send Packet

AbortComplete Remote DMA (Note 1)

Note 1

If a remote DMA operation is aborted and the remote byte count has not decremented to zero the data transfer port should

be read for a remote read or send packet or written to for a remote write This is required to ensure future correct operation

D6 D7

PS0 PS1

PAGE SELECT

These two encoded bits select which register page is to be accessed with addresses

RA0–3

PS1

PS0

Reserved

DP83907 датащи(PDF) 30 Page - National Semiconductor (TI)

DP83907 датащи(HTML) 30 Page - National Semiconductor (TI)

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70

датащи скачать

ссылки URL