AVR32768

15

32157A-AVR-12/10

9.4 Host mode, powered from bus connection

Figure 9-3.

USB host-powering connection example schematic.

USB_VBOF

VBUS

DM

DP

USB_ID

VBUS

D-

D+

ID

GND

5.0 volt

regulator

39 Ω

39 Ω

Table 9-3.

USB host-powering connection checklist.

Signal name

Recommended pin connection

Description

USB_VBOF

GPIO connected to VBUS 5.0V

regulator enable signal

USB power control pin

VBUS

Directly to connector

USB power pin

DM

39Ω series resistor

Placed as close as possible to DM

pin

Negative differential data line

DP

39Ω series resistor

Placed as close as possible to DP

pin

Positive differential data line

USB_ID

GPIO directly connected to

connector

USB identification pin. Pull-up on GPIO pin must be enabled

9.5 USB DFU ISP entry point

The ISP is activated according to the boot process conditions described in the boot

pin PA14 of UC3 C at logical 0 while releasing the reset. Once the ISP is activated, it

establishes a USB connection with the connected PC. This I/O should not be used by

the application if the USB DFU boot loader is required to program the application.