AT91SAM7XC256 Datasheet, PDF (443/675 Pages) ATMEL Corporation – Thumb-based Microcontrollers

AT91SAM7XC256/128 Preliminary
35.3.1 I/O Lines
DP and DM are not controlled by any PIO controllers. The embedded USB physical transceiver
is controlled by the USB device peripheral.
To reserve an I/O line to check VBUS, the programmer must first program the PIO controller to
assign this I/O in input PIO mode.
To reserve an I/O line to control the board pull-up, the programmer must first program the PIO
controller to assign this I/O in output PIO mode.
35.3.2
Power Management
The USB device peripheral requires a 48 MHz clock. This clock must be generated by a PLL
with an accuracy of ± 0.25%.
Thus, the USB device receives two clocks from the Power Management Controller (PMC): the
master clock, MCK, used to drive the peripheral user interface, and the UDPCK, used to inter-
face with the bus USB signals (recovered 12 MHz domain).
35.3.3 Interrupt
The USB device interface has an interrupt line connected to the Advanced Interrupt Controller
(AIC).
Handling the USB device interrupt requires programming the AIC before configuring the UDP.
6209B–ATARM–10-Feb-06
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