ATxmega32A4U Atmel Corporation, ATxmega32A4U Datasheet - Page 172

• 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

14.7.2
8331A–AVR–07/11
Frequency Capture
Figure 14-11. Input capture timing.
Selecting the frequency capture event action makes the enabled capture channel perform an
input capture and restart on positive edge events. This enables the timer/counter to measure the
period or frequency of a signal directly. The capture result will be the time (T) from the previous
timer/counter restart until the event occurred. This can be used to calculate the frequency (f) of
the signal:
Figure 14-12 on page 172
twice.
Figure 14-12. Frequency capture of an external signal.
Since all capture channels use the same counter (CNT), only one capture channel must be
enabled at a time. If two capture channels are used with different sources, the counter will be
restarted on positive edge events from both input sources, and the result will have no meaning.
f
=
external signal
events
CNT
CNT
1
-- -
T
BOTTOM
BOTTOM
events
TOP
MAX
Capture 0
shows an example where the period of an external signal is measured
Capture 1
Period (T)
Capture 2
Atmel AVR XMEGA AU
Capture 3
"capture"
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