Datasheet
SAM9261 [DATASHEET]
Atmel-6062O-ATARM-SAM9261-Datasheet_21-Jun-16
588
36.4.2 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 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.
36.4.3 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.
36.5 Typical Connection
Figure 36-2. Board Schematic to Interface Device Peripheral
36.5.1 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.
36.5.2 VBUS Monitoring
VBUS monitoring is required to detect host connection. VBUS monitoring is done using a standard PIO with
internal pullup disabled. When the host is switched off, it should be considered as a disconnect, the pullup must be
disabled in order to prevent powering the host through the pull-up resistor.
When the host is disconnected and the transceiver is enabled, then DDP and DDM are floating. This may lead to
over consumption. A solution is to connect 330 KΩ pulldowns on DP and DM. These pulldowns do not alter DDP
and DDM signal integrity.
A termination serial resistor must be connected to DP and DM. The resistor value is defined in the electrical
specification of the product (R
EXT
).
R
EXT
R
EXT
DDM
DDP
PIO
27 K
47 K
330 K
Type B
Connector
12
34
5V Bus Monitoring
330 K