AT32UC3A464 Atmel Corporation, AT32UC3A464 Datasheet - Page 81

• 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

8.4.1
8.4.2
8.4.3
8.4.4
8.5
8.5.1
8.5.1.1
8.5.1.2
32072G–11/2011
Functional Description
Power Management
Clocks
Interrupts
Debug Operation
RTC Operation
Source clock
Counter operation
The RTC remains operating in all sleep modes except Static mode. Interrupts are not available
in DeepStop mode.
The RTC can use the system RC oscillator as clock source. This oscillator is always enabled
whenever this module is active. Please refer to the Electrical Characteristics chapter for the
characteristic frequency of this oscillator (f
The RTC can also use the 32 KHz crystal oscillator as clock source. This oscillator must be
enabled before use. Please refer to the Power Manager chapter for details.
The clock for the RTC bus interface (CLK_RTC) is generated by the Power Manager. This clock
is enabled at reset, and can be disabled in the Power Manager. It is recommended to disable the
RTC before disabling the clock, to avoid freezing the RTC in an undefined state.
The RTC interrupt request line is connected to the interrupt controller. Using the RTC interrupt
requires the interrupt controller to be programmed first.
The RTC prescaler is frozen during debug operation, unless the OCD system keeps peripherals
running in debug operation.
The RTC is enabled by writing a one to the Enable bit in the Control Register (CTRL.EN). The
16-bit prescaler will then increment on the selected clock. The prescaler cannot be read or writ-
ten, but it can be reset by writing a one to the Prescaler Clear bit in CTRL register (CTRL.PCLR).
The 32KHz Oscillator Select bit in CTRL register (CTRL.CLK32) selects either the RC oscillator
or the 32 KHz oscillator as clock source (defined as INPUT in the formula below) for the
prescaler.
The Prescale Select field in CTRL register (CTRL.PSEL) selects the prescaler tapping, selecting
the source clock for the RTC:
When enabled, the RTC will increment until it reaches TOP, and then wraps to 0x0. The status
bit TOPI in Interrupt Status Register (ISR) is set to one when this occurs. From 0x0 the counter
will count TOP+1 cycles of the source clock before it wraps back to 0x0.
f
RTC
=
f
INPUT
RC
).
2 ⁄
(
PSEL
+
1
)
81