Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Data Sheet

SAM4E [DATASHEET]

Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14

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The USB physical transceiver is integrated into the product. The bidirectional differential signals DDP and DDM
are available from the product boundary.

One I/O line may be used by the application to check that VBUS is still available from the host. Self-powered
devices may use this entry to be notified that the host has been powered off. In this case, the pull-up on DDP must
be disabled in order to prevent feeding current to the host. The application should disconnect the transceiver, then
remove the pull-up.

The USB pins are shared with PIO lines. By default, the USB function is activated, and pins DDP and DDM are
used for USB. To configure DDP or DDM as PIOs, the user needs to configure the system I/O configuration
register (CCFG_SYSIO) in the MATRIX.

The USB device peripheral requires a 48 MHz clock. This clock must be generated by a PLL driven by a clock
source with an accuracy of ± 0.25% (note that the fast RC oscillator cannot be used).

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 interface with the bus USB signals (recovered
12 MHz domain).

WARNING: The UDP peripheral clock in the Power Management Controller (PMC) must be enabled before any
read/write operations to the UDP registers including the UDP_TXVC register. 

The USB device interface has an interrupt line connected to the Interrupt Controller. 

Handling the USB device interrupt requires programming the Interrupt Controller before config-uring the UDP. 

UDP

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