C8051F340/1/2/3/4/5/6/7

SFR Definition 16.1. USB0XCN: USB0 Transceiver Control

R/W

R/W

R/W

R/W

R/W

R

R

R

Reset Value

PREN

PHYEN

SPEED

PHYTST1

PHYTST0

DFREC

Dp

Dn

Bit7

Bit6

Bit5

Bit4

Bit3

Bit2

Bit1

Bit0

00000000

SFR Address:

 

 

 

 

 

 

0xD7

Bit7:

PREN: Internal Pull-up Resistor Enable

 

 

 

 

The location of the pull-up resistor (D+ or D–) is determined by the SPEED bit.

 

0: Internal pull-up resistor disabled (device effectively detached from the USB network).

 

1: Internal pull-up resistor enabled when VBUS is present (device attached to the USB net-

 

work).

 

 

 

 

 

Bit6:

PHYEN: Physical Layer Enable

 

 

 

 

This bit enables/disables the USB0 physical layer transceiver.

 

0: Transceiver disabled (suspend).

 

 

 

 

1: Transceiver enabled (normal).

 

 

 

Bit5:

SPEED: USB0 Speed Select

 

 

 

 

This bit selects the USB0 speed.

 

 

 

 

0: USB0 operates as a Low Speed device. If enabled, the internal pull-up resistor appears

 

on the D– line.

 

 

 

 

 

 

1: USB0 operates as a Full Speed device. If enabled, the internal pull-up resistor appears on

 

the D+ line.

 

 

 

 

 

Bits4–3:

PHYTST1–0: Physical Layer Test

 

 

 

 

These bits can be used to test the USB0 transceiver.

 

 

 

 

 

 

 

 

 

 

 

PHYTST[1:0]

Mode

 

D+

D–

 

 

00b

Mode 0: Normal (non-test mode)

 

X

X

 

 

01b

Mode 1: Differential ‘1’ Forced

 

1

0

 

 

10b

Mode 2: Differential ‘0’ Forced

 

0

1

 

 

11b

Mode 3: Single-Ended ‘0’ Forced

 

0

0

 

Bit2:

DFREC: Differential Receiver

 

 

 

 

The state of this bit indicates the current differential value present on the D+ and D– lines

 

when PHYEN = ‘1’.

 

 

 

 

0: Differential ‘0’ signaling on the bus.

 

 

 

 

1: Differential ‘1’ signaling on the bus.

 

 

 

Bit1:

Dp: D+ Signal Status

 

 

 

 

This bit indicates the current logic level of the D+ pin.

 

 

 

 

0: D+ signal currently at logic 0.

 

 

 

 

1: D+ signal currently at logic 1.

 

 

 

Bit0:

Dn: D- Signal Status

 

 

 

 

This bit indicates the current logic level of the D– pin.

 

 

 

0: D– signal currently at logic 0.

1: D– signal currently at logic 1.

Rev. 0.5

165

Page 165
Image 165
Silicon Laboratories C8051F344, C8051F347, C8051F346 SFR Definition 16.1. USB0XCN USB0 Transceiver Control, PHYTST10