ATxmega256A3 Atmel Corporation, ATxmega256A3 Datasheet - Page 158

• Manufacturer Part Number: ATxmega256A3
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3

• Flash (kbytes): 256 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 50
• Ext Interrupts: 50
• Usb Speed: No
• Usb Interface: No
• Spi: 10
• Twi (i2c): 2
• Uart: 7
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 4
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 16
• Eeprom (bytes): 4096
• 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: 7
• Output Compare Channels: 22
• Input Capture Channels: 22
• Pwm Channels: 22
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

14.7.2
14.7.3
8077H–AVR–12/09
Frequency Capture
Pulse-width Capture
Selecting the frequency capture event action, makes the enabled capture channel perform an
input capture and restart on positive edge events. This enables Timer/Counter to use capture to
measure the period or frequency of a signal directly. The capture result will be the time, T, from
the previous Timer/Counter restart and until the event occurred. This can be used to calculate
the frequency, f, of the signal:
Figure 14-10 on page 158
nal signal.
Figure 14-10. Frequency capture of an external signal
Since all capture channels uses the same Counter (CNT), only one capture channels must be
enabled at a time. If two capture channels are used with different source, the Counter will be
restarted on positive edge events from both input sources, and the result from the input capture
will have no meaning.
Selecting the pulse-width measure event action makes the enabled compare channel perform
the input capture action on falling edge events and the restart action on rising edge events. The
counter will then start at zero at every start of a pulse and the input capture will be performed at
the end of the pulse. The event source must be an I/O pin and the sense configuration for the pin
must be set up to generate an event on both edges.
ple where the pulse width is measured twice for an external signal.
f
=
external signal
events
CNT
1
-- -
T
MAX
BOT
shows an example where the Period is measured twice for an exter-
Period (T)
Figure 14-11 on page 159
XMEGA A
shows and exam-
"capture"
158