SAM7SE256 Atmel Corporation, SAM7SE256 Datasheet - Page 558

• Manufacturer Part Number: SAM7SE256
• Manufacturer: Atmel Corporation

Specifications of SAM7SE256

• Flash (kbytes): 256 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 48 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 88
• Ext Interrupts: 88
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Twi (i2c): 1
• Uart: 3
• Ssc: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 384
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 32
• Self Program Memory: NO
• External Bus Interface: 1
• Dram Memory: sdram
• Nand Interface: Yes
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8/3.3
• Operating Voltage (vcc): 3.0 to 3.6
• Fpu: No
• Mpu / Mmu: Yes / No
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

38.4
Figure 38-2. Board Schematic to Interface Device Peripheral
38.4.1
38.4.2
558
Typical Connection
SAM7SE512/256/32
USB Device Transceiver
VBUS Monitoring
PIO
DDM
DDP
5V Bus Monitoring
The USB device transceiver is embedded in the product. A few discrete components are
required as follows:
VBUS monitoring is required to detect host connection. VBUS monitoring is done using a stan-
dard 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 DDP and
DDM. These pulldowns do not alter DDP and DDM signal integrity.
A termination serial resistor must be connected to DDP and DDM. The resistor value is defined
in the electrical specification of the product (R
• the application detects all device states as defined in chapter 9 of the USB specification;
• to reduce power consumption the host is disconnected
• for line termination.
– VBUS monitoring
47 K
27 K
R
R
EXT
EXT
330 K
EXT
).
330 K
2
3
Connector
Type B
1
4
6222F–ATARM–14-Jan-11