UPD72850A Просмотр технического описания (PDF) - NEC => Renesas Technology

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UPD72850A

IEEE1394 400Mbps PHY

NEC => Renesas Technology 

µPD72850A

3.2.2 Cable Interface Circuit

Each port is configured with two twisted-pairs of TpA and TpB.

TpA and TpB are used to monitor the state of the Transmit/Receive line, control signals, data and cables.

During transmission to the IEEE1394 bus, the Data/Strobe signal received from the Link layer controller is

encoded, converted from parallel to serial and transmitted.

While receiving from the IEEE1394 bus, the Data/Strobe signal from TpA, TpB is converted from serial to parallel

after synchronization by SCLK, then transmitted to the Link layer controller in 2/4/8 bits according to the data rate of

100/200/400 Mbps.

The bus arbitration for TpA and TpB and the state of the line are monitored by the built-in comparator. The state of

the IEEE1394 bus is transmitted to the state machine in the LSI.

3.2.3 Unused Ports

TpAp, TpAn : Not connected

TpBp, TpBn : AGND

TpBias : Connected to AGND using a 1.0 µF load capacitor

3.2.4 CPS

An external resistance of 390 kΩ is connected in series to the power cable to monitor the power of the power

cable. If the cable power falls under 7.5 V there is an indication to the Link layer controller that the power has failed.

3.3 Suspend/Resume

3.3.1 Suspend/Resume On Mode (SUS/RES = “H”)

There are two ways of transition from the active status to the suspended status.

One is when the receipt of a remote command packet that sets the initiate suspend command. After that, the PHY

transmits a remote confirmation packet with the ok bit set, subsequently signals TX_SUSPEND to the connected

peer PHY with the port which specified by the port field in the remote command packet, and then the PHY port

transitions to the suspended state.

The other is when the receipt of a RX_SUSPEND or RX_DISABLE_NOTIFY signal. When the port observes

RX_SUSPEND, it transmits TX_SUSPEND to the active ports.

The TX_SUSPEND transmitted propagates until it reaches a leaf node. The PHY port transitions to the suspended

state. The propagation of the suspended domain may be blocked by a PHY compliant with IEEE Std 1394-1995, a

disabled or a suspended port.

Any one of a number of reasons may cause a suspended port to attempt to resume normal operations:

• Bias is detected and there is no fault condition;

• A resume packet is received or transmitted by the PHY;

• A remote command packet that sets the resume port command is received; or

• Either port of a node without active ports detects bias.

3.3.2 Suspend/Resume Off Mode (SUS/RES = “L”)

• Remote command packet is ignored.

• Resume packet is ignored.

• Disabled, Int_enable and resume_int bits in PHY register are ignored.

• Responses to Remote access packet.

• Detects the connection of the port in TpBias.

Data Sheet S14452EJ1V0DS00

19

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