ATxmega128B1 Atmel Corporation, ATxmega128B1 Datasheet - Page 114

• Manufacturer Part Number: ATxmega128B1
• Manufacturer: Atmel Corporation

Specifications of ATxmega128B1

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 53
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Segment Lcd: 160
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 4
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 8
• Eeprom (bytes): 2048
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 10
• Input Capture Channels: 10
• Pwm Channels: 10
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

10.4
10.5
8291A–AVR–10/11
Window Mode Operation
Watchdog Timer Clock
Figure 10-1. Normal mode operation.
In window mode operation, the WDT uses two different timeout periods, a "closed" window time-
out period (TO
defines a duration of from 8ms to 8s where the WDT cannot be reset. If the WDT is reset during
this period, the WDT will issue a system reset. The normal WDT timeout period, which is also
8ms to 8s, defines the duration of the "open" period duirng which the WDT can (and should) be
reset. The open period will always follow the closed period, and so the total duration of the time-
out period is the sum of the closed window and the open window timeout periods. The default
closed window timeout period is controlled by fuses (both open and closed periods are con-
trolled by fuses). The window mode operation is illustrated in
Figure 10-2. Window mode operation.
The WDT is clocked from the 1kHz output from the 32kHz ultra low power (ULP) internal oscilla-
tor. Due to the ultra low power design, the oscillator is not very accurate, and so the exact
timeout period may vary from device to device. When designing software which uses the WDT,
this device-to-device variation must be kept in mind to ensure that the timeout periods used are
valid for all devices. For more information on ULP oscillator accuracy, consult the device
datasheet.
WDTW
) and the normal timeout period (TO
Atmel AVR XMEGA B
WDT
). The closed window timeout period
Figure
10-2.
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