USB3300 datasheet(26/53 Pages) MICROCHIP

26 / 53 page

USB3300

DS00001783B-page 26

 2014-2015 Microchip Technology Inc.

6.1.5.2

ULPI Register Read

A ULPI register read operation is given in Figure 6-5. The Link drives a TXD CMD byte with DATA[7:6] = 11h for a reg-

ister read. DATA[5:0] of the ULPI TXD command bye contain the register address.

At T0, the Link will place the TXD CMD on the databus. At T2, the PHY will bring NXT high, signaling that the Link it is

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

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

and the PHY drives the requested register onto the databus. At T5, the Link will read the databus 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 com-

mand at T6.

6.1.6

ULPI RXD CMD

The Link needs several more important states of information which were provided by the linestate[1:0], rxactive, rxvalid

and rxerror. When an implementing the OTG functions the Vbus and ID pin states must also be transferred into the Link.

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

is given in the Table 6-5, "ULPI RX CMD Encoding".

Transfer of the RXD CMD byte occurs when in Synchronous Mode when the PHY has control of the bus. Transfers of

the RXD CMD occur after: a transmit cmd has issued STP, a linestate change when not transmitting, a USB receive, or

an interrupt event occurs.

In Figure 6-2, "ULPI Digital Block Diagram", the ULPI Protocol Block determines when to send an RXD CMD. When a

linestate change occurs the RXD CMD is sent immediately if the DIR output is low.

When a USB Receive is occurring RXD CMDs are sent when ever NXT = 0 and DIR = 1. When a USB Transmit occurs

the RXD CMDs are returned to the Link after the STP is asserted ending the Link to USB3300 transfer of the bytes to

be sent on the transmit.

To summarize a RXD CMD transfer occurs:

• when DIR is low and a linestate change occurs.

• when Vbus and/or ID comparators change state.

• during a USB receive when NXT is low.

• after STP is asserted during a USB transmit cmd.

FIGURE 6-5:

ULPI REGISTER READ

DIR

CLK

DATA[7:0]

STP

NXT

Txd Cmd Reg

Read

Idle

Reg Data

Turn around

Idle

USB3300 датащи(PDF) 26 Page - Microchip Technology

USB3300 датащи(HTML) 26 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

датащи скачать

ссылки URL