ATxmega16A4U Atmel Corporation, ATxmega16A4U Datasheet - Page 74

• Manufacturer Part Number: ATxmega16A4U
• Manufacturer: Atmel Corporation

Specifications of ATxmega16A4U

• Flash (kbytes): 16 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): 3.3
• 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

6.5
6.6
6.7
6.7.1
8331A–AVR–07/11
Event Timing
Filtering
Quadrature Decoder
Quadrature Operation
An event normally lasts for one peripheral clock cycle, but some event sources, such as a low
level on an I/O pin, will generate events continuously. Details on this are described in the
datasheet for each peripheral, but unless otherwise stated, an event lasts for one peripheral
clock cycle.
It takes a maximum of two peripheral clock cycles from when an event is generated until the
event actions in other peripherals are triggered. This ensures short and 100% predictable
response times, independent of CPU or DMA controller load or software revisions.
Each event channel includes a digital filter. When this is enabled, an event must be sampled
with the same value for a configurable number of system clock cycles before it is accepted. This
is primarily intended for pin change events.
The event system includes three quadrature decoders (QDECs), which enable the device to
decode quadrature input on I/O pins and send data events that a timer/counter can decode to
count up, count down, or index/reset.
decoder data events are available, how they are decoded, and how they can be generated. The
QDECs and related features and control and status registers are available for event channels 0,
2, and 4.
Table 6-2.
A quadrature signal is characterized by having two square waves that are phase shifted 90
degrees relative to each other. Rotational movement can be measured by counting the edges of
the two waveforms. The phase relationship between the two square waves determines the
direction of rotation.
STROBE
0
0
1
1
DATA
Quadrature decoder data events.
0
1
0
1
Data Event User
No event
Index/reset
Count down
Count up
Table 6-2 on page 74
Atmel AVR XMEGA AU
Signaling Event User
No event
No event
Signaling event
Signaling event
summarizes which quadrature
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