AT32UC3A464 Atmel Corporation, AT32UC3A464 Datasheet - Page 93

• Manufacturer Part Number: AT32UC3A464
• Manufacturer: Atmel Corporation

Specifications of AT32UC3A464

• Flash (kbytes): 64 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 66 MHz
• Cpu: 32-bit AVR
• Hardware Qtouch Acquisition: No
• Usb Transceiver: 1
• Usb Speed: Hi-Speed
• Usb Interface: Device + OTG
• Spi: 6
• Twi (i2c): 2
• Uart: 4
• Ssc: 1
• Sd / Emmc: 2
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 128
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: Yes
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 3.0 to 3.6
• Operating Voltage (vcc): 3.0 to 3.6
• Fpu: No
• Timers: 6
• Output Compare Channels: 6
• Input Capture Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

9.5
9.6
Table 9-1.
32072G–11/2011
Offset
0x00
0x04
Functional Description
User Interface
WDT Register Memory Map
The WDT is enabled by writing a one to the Enable bit in the Control register (CTRL.EN). This
also enables the system RC clock (CLK_RCSYS) for the prescaler. The Prescale Select field
(PSEL) in the CTRL register selects the watchdog time-out period:
The next time-out period will begin as soon as the watchdog reset has occurred and count down
during the reset sequence. Care must be taken when selecting the PSEL field value so that the
time-out period is greater than the startup time of the chip, otherwise a watchdog reset can reset
the chip before any code has been run.
To avoid accidental disabling of the watchdog, the CTRL register must be written twice, first with
the KEY field set to 0x55, then 0xAA without changing the other bits. Failure to do so will cause
the write operation to be ignored, and the CTRL register value will not change.
The Clear register (CLR) must be written with any value with regular intervals shorter than the
watchdog time-out period. Otherwise, the device will receive a soft reset, and the code will start
executing from the boot vector.
When the WDT is enabled, it is not possible to enter Static mode. Attempting to do so will result
in entering Shutdown mode, leaving the WDT operational.
T
Control Register
WDT
Clear Register
Register
= 2
(PSEL+1)
/ f
RC
Register Name
CTRL
CLR
Read/Write
Write-only
Access
0x00000000
0x00000000
Reset
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