ATxmega128B1 Atmel Corporation, ATxmega128B1 Datasheet - Page 69

• Manufacturer Part Number: ATxmega128B1
• Manufacturer: Atmel Corporation

Specifications of ATxmega128B1

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 53
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Segment Lcd: 160
• 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
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 8
• 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: 3
• Output Compare Channels: 10
• Input Capture Channels: 10
• Pwm Channels: 10
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

6.7
6.7.1
8291A–AVR–10/11
Quadrature Decoder
Quadrature Operation
The event system includes one quadrature decoder (QDEC), 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.
events are available, how they are decoded, and how they can be generated. The QDEC and
related features and control and status registers are available for event channel 0.
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.
Figure 6-4.
Figure 6-4
QDPH90 are the two quadrature signals. When QDPH90 leads QDPH0, the rotation is defined
as positive or forward. When QDPH0 leads QDPH90, the rotation is defined as negative or
reverse. The concatenation of the two phase signals is called the quadrature state or the phase
state.
In order to know the absolute rotary displacement, a third index signal (QDINDX) can be used.
This gives an indication once per revolution.
STROBE
0
0
1
1
shows typical quadrature signals from a rotary encoder. The signals QDPH0 and
DATA
Quadrature decoder data events.
Quadrature signals from a rotary encoder.
Forward Direction
0
1
0
1
Backward
Direction
Data Event User
No event
Index/reset
Count down
Count up
Table 6-2 on page 69
QDPH90
QDPH90
QDINDX
QDINDX
QDPH0
QDPH0
00
01
summarizes which quadrature decoder data
1 cycle / 4 states
10
11
Atmel AVR XMEGA B
11
10
Signaling Event User
No event
No event
Signaling event
Signaling event
01
00
69