UPD72871 datasheet(19/48 Pages) NEC

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Preliminary Data Sheet S13925EJ2V0DS00

µµµµPD72870,72871

Table 2-1. Bit Field Description (2/3)

Field

Size

R/W

Reset value

Description

Extended

111

Shows the extended register map.

Total_ports

0011

0001

Supported port number.

0011: 3port (

µPD72870)

0001: 1port (

µPD72871)

Max_speed

010

Indicate the maximum speed that this node supports.

010: 98.304, 196.608 and 393.216 Mbps

Delay

0010

Indicate worst case repeating delay time. 144+(2 x 20)=184 nsec

Link_active

R/W

Link active.

1: Enable

0: Disable

The logical AND status of this bit and LPS.

State will be referred to “L bit” of Self-ID Packet#0.

The LPS is a PHY/Link interface signal and is defined in P1394a draft 2.0. It

is an internal signal in the

µPD72870,72871.

Contender

R/W

See

Description

Contender.

“1” indicate this node support bus manager function. This bit will be referred

to “C bit” of Self-ID Packet#0.

The reset data is depending on CMC pin setting.

CMC pin condition

1: Pull up (Contender)

0: Pull down (Non Contender)

Jitter

010

The difference of repeating time (Max.-Min.). (2+1) x 20=60 nsec

Pwr_class

R/W

See

Description

Power class.

Please refer to IEEE1394 -1995 [4.3.4.1].

This bit will be referred to Pwr field of Self-ID Packet#0.

The reset data will be determined by PC0-PC2 Pin status.

Resume_int

R/W

Resume interrupt enable. When set to 1, if any one port does resume, the

Port_event bit becomes 1.

ISBR

R/W

Initiate short (arbitrated) bus reset.

Setting to 1 acquires the bus and begins short bus reset.

Short bus reset signal output : 1.3

µsec

Returns to 0 at the beginning of the bus reset.

Loop

R/W

Loop detection output.

1: Detection

Writing 1 to this bit clears it to 0.

Writing 0 has no effect.

Pwr_fail

R/W

Power cable disconnect detect.

It becomes 1 when there is a change from 1 to 0 in the CPS bit.

Writing 1 to this bit clears it to 0.

Writing 0 has no effect.

Timeout

R/W

Arbitration state machine time-out.

Writing 1 to this bit clears it to 0.

Writing 0 has no effect.

UPD72871 Datasheet(PDF) 19 Page - NEC

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