ATxmega64A4U Atmel Corporation, ATxmega64A4U Datasheet - Page 136

• Manufacturer Part Number: ATxmega64A4U
• Manufacturer: Atmel Corporation

Specifications of ATxmega64A4U

• Flash (kbytes): 64 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 34
• Ext Interrupts: 34
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 2
• Twi (i2c): 2
• Uart: 5
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 2
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 4
• 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: 5
• Output Compare Channels: 16
• Input Capture Channels: 16
• Pwm Channels: 16
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

12.6.2
8331A–AVR–07/11
Round-robin Scheduling
Figure 12-2. Static priority.
To avoid the possible starvation problem for low-level interrupts with static priority, where some
interrupts might never be served, the PMIC offers round-robin scheduling for low-level interrupts.
When round-robin scheduling is enabled, the interrupt vector address for the last acknowledged
low-level interrupt will have the lowest priority the next time one or more interrupts from the low
level is requested.
Figure 12-3. Round-robin scheduling.
IV EC x las t ack now le dge d
inte rrupt
IV EC x+1
IV EC N
IV EC 0
IV EC x
:
:
:
:
:
:
Lowes t Addres s
Highes t Addres s
Low est Priority
Highest Priority
IVEC x+1
IVEC N
IVEC 0
IVEC x
:
:
:
:
:
:
IV EC x+1 las t ack now le dge d
inte rrupt
Atmel AVR XMEGA AU
IV EC x+1
IV EC x+2
IV EC N
IV EC 0
IV EC x
Highes t Priority
Lowes t Priority
:
:
:
:
:
:
Low est Priority
Highest Priority
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