USB334X datasheet(48/92 Pages) MICROCHIP

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USB334x

DS00002646A-page 48

 2009-2018 Microchip Technology Inc.

6.3

USB334x Receiver

The following section describes how the USB334x 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 USB334x asserts DIR to take con-

trol of the bus. The timing of RXCMD is shown in the figure below. The USB334x 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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