USB3320 datasheet(38/70 Pages) MICROCHIP

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USB3320

DS00001792B-page 38

 2014-2015 Microchip Technology Inc.

At T0, the Link will place the TXD CMD on the data bus. At T2, the transceiver will bring NXT high, signaling the Link it

is ready to accept the data transfer. At T3, the transceiver reads the TXD CMD, determines it is a register read, and

asserts DIR to gain control of the bus. The transceiver will also de-assert NXT. At T4, the bus ownership has transferred

back to the transceiver and the transceiver drives the requested register onto the data bus. At T5, the Link will read the

data bus and the transceiver 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 transceiver 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 transceiver reads the

extended address, and asserts DIR to gain control of the bus. The transceiver will also de-assert NXT. At T5, the bus

ownership has transferred back to the transceiver and the transceiver drives the requested register onto the data bus.

At T6, the Link will read the data bus and the transceiver 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.

6.2.3

ULPI RXCMD

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

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

ferred to the Link.

ULPI defines a Receive Command Byte (RXCMD) that contains this information. The Encoding of the RXCMD byte is

given in the Table 6-3.

Transfer of the RXCMD byte occurs in Synchronous Mode when the transceiver has control of the bus. The ULPI Pro-

tocol Block shown in Figure 6-1 determines when to send an RXCMD.

A RXCMD can occur:

• When a linestate change occurs.

• When VBUS or ID comparators change state.

• During a USB receive when NXT is low.

• After the USB3320 deasserts DIR and STP is low during start-up

• After the USB3320 exits Low Power Mode, Serial Modes, or Carkit Mode after detecting that the Link has de-

asserted STP, and DIR is low.

When a USB Receive is occurring, RXCMD’s are sent whenever NXT = 0 and DIR = 1. During a USB Transmit, the

RXCMD’s are returned to the Link after STP is asserted.

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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