ATxmega128B1 Atmel Corporation, ATxmega128B1 Datasheet - Page 70

• 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

6.7.2
8291A–AVR–10/11
QDEC Setup
For a full QDEC setup, the following is required:
The following procedure should be used for QDEC setup:
The angle of a quadrature encoder attached to QDPH0, QDPH90 (and QINDX) can now be read
directly from the timer/counter count register. If the count register is different from BOTTOM
when the index is recognized, the timer/counter error flag is set. Similarly, the error flag is set if
the position counter passes BOTTOM without the recognition of the index.
• Two or three I/O port pins for quadrature signal input
• Two event system channels for quadrature decoding
• One timer/counter for up, down, and optional index count
1. Choose two successive pins on a port as QDEC phase inputs.
2. Set the pin direction for QDPH0 and QDPH90 as input.
3. Set the pin configuration for QDPH0 and QDPH90 to low level sense.
4. Select the QDPH0 pin as a multiplexer input for an event channel, n.
5. Enable quadrature decoding and digital filtering in the event channel.
6. Optional:
7. Set quadrature decoding as the event action for a timer/counter.
8. Select event channel n as the event source for the timer/counter.
• Set the period register of the timer/counter to ('line count' * 4 - 1), the line count of the
• Enable the timer/counter without clock prescaling.
quadrature encoder.
a. Set up a QDEC index (QINDX).
b. Select a third pin for QINDX input.
c. Set the pin direction for QINDX as input.
d. Set the pin configuration for QINDX to sense both edges.
e. Select QINDX as a multiplexer input for event channel n+1
f.
g. Select the index recognition mode for event channel n+1.
Set the quadrature index enable bit in event channel n+1.
Atmel AVR XMEGA B
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