Datasheet

 2017 Microchip Technology Inc. DS60001516A-page 659
SAM9G20
A USB 2.0 full-speed pad is embedded and controlled by the Serial Interface Engine (SIE).
The signal external_resume is optional. It allows the UDP peripheral to wake up once in system mode. The host is then notified that the
device asks for a resume. This optional feature must be also negotiated with the host during the enumeration.
36.3 Product Dependencies
For further details on the USB Device hardware implementation, see the specific Product Properties document.
The USB physical transceiver is integrated into the product. The bidirectional differential signals DP and DM 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.
36.3.1 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.
36.3.2 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 periph-
eral 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_TXCV register.
36.3.3 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.
36.4 Typical Connection
Figure 36-2: Board Schematic to Interface Device Peripheral
36.4.1 USB Device Transceiver
The USB device transceiver is embedded in the product. A few discrete components are required as follows:
• the application detects all device states as defined in chapter 9 of the USB specification;
- VBUS monitoring
• to reduce power consumption the host is disconnected
• for line termination.
R
EXT
R
EXT
DDM
DDP
PIO
27 K
47 K
Type B
Connector
12
3 4
5V Bus Monitoring