ATxmega32A4U Atmel Corporation, ATxmega32A4U Datasheet - Page 324

• Manufacturer Part Number: ATxmega32A4U
• Manufacturer: Atmel Corporation

Specifications of ATxmega32A4U

• Flash (kbytes): 32 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 34
• Ext Interrupts: 34
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 7
• 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): 1024
• 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

26. CRC - Cyclic Redundancy Check
26.1
26.2
8331A–AVR–07/11
Features
Overview
•
•
•
•
A cyclic redundancy check (CRC) is an error detection technique test algorithm used to find
accidental errors in data, and it is commonly used to determine the correctness of a data trans-
mission, and data present in the data and program memories. A CRC takes a data stream or a
block of data as input and generates a 16- or 32-bit output that can be appended to the data and
used as a checksum. When the same data are later received or read, the device or application
repeats the calculation. If the new CRC result does not match the one calculated earlier, the
block contains a data error. The application will then detect this and may take a corrective
action, such as requesting the data to be sent again or simply not using the incorrect data.
Typically, an n-bit CRC applied to a data block of arbitrary length will detect any single error
burst not longer than n bits (any single alteration that spans no more than n bits of the data), and
will detect the fraction 1-2
ports two commonly used CRC polynomials; CRC-16 (CRC-CCITT) and CRC-32 (IEEE 802.3).
• CRC-16:
• CRC-32:
Cyclic redundancy check (CRC) generation and checking for
Integrated with flash memory, DMA controller and CPU
CRC polynomial software selectable to
Zero remainder detection
– Communication data
– Program or data in flash memory
– Data in SRAM and I/O memory space
– Continuous CRC on data going through a DMA channel
– Automatic CRC of the complete or a selectable range of the flash memory
– CPU can load data to the CRC generator through the I/O interface
– CRC-16 (CRC-CCITT)
– CRC-32 (IEEE 802.3)
Hex value:
Hex value:
Polynomial:
Polnomial:
x
0x1021
x
0x04C11DB7
16
32
-n
+x
+x
of all longer error bursts. The CRC module in XMEGA devices sup-
12
26
+x
+x
5
23
+1
+x
22
+x
16
+x
12
+x
11
Atmel AVR XMEGA AU
+x
10
+
x
8
+x
7
+x
5
+x
4
+x
2
+x+1
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