USB3370 datasheet(38/75 Pages) MICROCHIP

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USB3370

DS00001915B-page 38

 2012 - 2015 Microchip Technology Inc.

PHY drives the requested register onto the data bus. At T5, the Link will read the data bus and the PHY will drop DIR

low returning control of the bus back to the Link. After the turn around cycle, the Link must drive a ULPI Idle command

at T6.

A ULPI extended register read operation is shown in Figure 6-6.To read an extended register, the Link writes the TX

CMD with the address set to 2Fh. At T2, the PHY will assert NXT, signaling the Link it is ready to accept the extended

address. At T3, the Link places the extended register address on the bus. At T4, the PHY reads the extended address,

and asserts DIR to gain control of the bus. The PHY will also de-assert NXT. At T5, the bus ownership has transferred

back to the PHY and the PHY drives the requested register onto the data bus. At T6, the Link will read the data bus and

the PHY will de-assert DIR returning control of the bus back to the Link. After the turn around cycle, the Link must drive

a ULPI Idle command at T6.

6.3

USB3370 Receiver

The following section describes how the USB3370 uses the ULPI interface to receive USB signaling and transfer status

information to the Link. This information is communicated to the Link using RX Commands to relay bus status and

received USB packets.

6.3.1

ULPI RECEIVE COMMAND (RX CMD)

The ULPI Link needs information which was provided by the following pins in a UTMI implementation: linestate[1:0],

rxactive, rxvalid, rxerror, and VbusValid. When implementing the OTG functions, the VBUS and ID pin states must also

be transferred to the Link. ULPI defines a Receive Command Byte (RXCMD) that contains this information.

An RXCMD can be sent a any time the bus is idle. The RXCMD is initiated when the USB3370 asserts DIR to take con-

trol of the bus. The timing of RXCMD is shown in the figure below. The USB3370 can send single or back to back

RXCMD’s as required. The Encoding of the RXCMD byte is given in the Table 6-3.

FIGURE 6-6:

ULPI EXTENDED REGISTER READ IN SYNCHRONOUS MODE

DIR

CLK

DATA[7:0]

STP

NXT

TXD CMD

extended reg read

Idle

Reg Data

Turn around

Idle

Extended

address

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