SAM3S8C Atmel Corporation, SAM3S8C Datasheet - Page 955

• Manufacturer Part Number: SAM3S8C
• Manufacturer: Atmel Corporation

36.4
36.4.1
36.4.2
36.4.3
11090A–ATARM–10-Feb-12
11090A–ATARM–10-Feb-12
Product Dependencies
I/O Lines
Power Management
Interrupt
For further details on the USB Device hardware implementation, see the specific Product Prop-
erties document.
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 pullup on DP must be disabled in order to prevent feeding current to the host. The
application should disconnect the transceiver, then remove the pullup.
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
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).
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.
Table 36-3.
Instance
UDP
Peripheral IDs
34
ID
SAM3S8/SD8
SAM3S8/SD8
955
955