USB3317C_V01 datasheet(49/76 Pages) SMSC

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Hi-Speed USB Transceiver with 1.8V-3.3V ULPI Interface - 26MHz Reference Clock

Datasheet

SMSC USB3317 REV C

Revision 2.1 (06-02-10)

DATASHEET

6.4

Carkit Mode

The USB3317 includes Carkit Mode to support a USB UART Mode.

60MHz clock is stopped to conserve power by default. The Link may configure the 60MHz clock to

continue by setting the ClockSuspendM bit of Interface Control before entering Carkit Mode. If set, the

60 MHz clock will continue during the of operation.

In Carkit Mode, interrupts are possible from unmasked sources. The state of each interrupt source is

sampled prior to the assertion of DIR and this is compared against the asynchronous level from

interrupt source. In Carkit Mode, the Linestate signals are not available per the ULPI specification.

Exiting Carkit Mode is the same as exiting Low Power Mode as described in Section 6.2.6.2. The Link

must assert STP to signal the PHY to exit serial mode. When the PHY can accept a command, DIR

is de-asserted and the PHY will wait until the Link de-asserts STP to resume synchronous ULPI

operation. The RESETB pin can also be pulsed low to reset the USB3317 and return it to Synchronous

Mode.

6.4.1

USB UART Mode

The USB3317 can be placed into UART Mode by first setting the TxdEn and RxdEn bits in the Carkit

Control register. Then the Link can set the CarkitMode bit in the Interface Control register. The TxdEn

and RxdEn bits must be written before the CarkitMode bit. After the CarkitMode bit is set, the ULPI

interface will become redefined as described in Table 6.7, and the USB3317 will transmit data through

the DATA[0] to DM of the USB connector and receive data on DP and pass the information the Link

on DATA[1].

When entering UART mode, the regulator output will automatically switch to the value configured by

the UART RegOutput bits in the USB IO & Power Management register and a 125K RCD pull-up will

be applied internally to DP and DM. This will hold the UART in its default operating state.

While in UART mode, the transmit edge rates can be set to either the Full Speed USB or Low Speed

USB edge rates by using the XcvrSelect[1:0] bits in the Function Control register.

rx_rcv

DATA[6]

OUT

Differential receive data from DP and DM.

Reserved

DATA[7]

OUT

Driven Low.

Table 6.7 Pin Definitions in Carkit Mode

SIGNAL

CONNECTED

DIRECTION

DESCRIPTION

txd

DATA[0]

UART TXD signal that is routed to the DM pin if the TxdEn

is set in the Carkit Control register.

rxd

DATA[1]

OUT

UART RXD signal that is routed to the DP pin if the RxdEn

bit is set in the Carkit Control register.

reserved

DATA[2]

OUT

Driven Low.

int

DATA[3]

OUT

Asserted when any unmasked interrupt occurs. Active high.

reserved

DATA[4:7]

OUT

Driven Low.

Table 6.6 Pin Definitions in 6 pin Serial Mode (continued)

SIGNAL

CONNECTED

DIRECTION

DESCRIPTION

USB3317C Datasheet(PDF) 49 Page - SMSC Corporation

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