AT32UC3C2512C Automotive Atmel Corporation, AT32UC3C2512C Automotive Datasheet - Page 1046

• Manufacturer Part Number: AT32UC3C2512C Automotive
• Manufacturer: Atmel Corporation

34. Quadrature Decoder (QDEC)
34.1
34.2
Figure 34-1. Quadrature Signals Description
9166C–AVR-08/11
Features
Overview
Rev.: 1.0.0.0
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The QDEC is used in rotating motion systems for position and speed detection. It decodes
quadrature signals, normally two 90 degrees out-of-phases pulses, into count and direction
informations. The quadrature signals are usually generated by a wheel with periodic transparent
gaps (a.k.a. lines) and an optical system composed of one light source and 2 sensors.
The phase signals are labelled QEPA and QEPB. If QEPA leads QEPB, the rotation direction is
defined as positive. If QEPB leads QEPA, the rotation direction is defined as negative. Each
time a line passes the sensor, a counter register (CNT.PC) is incremented or decremented
depending of the rotation direction. A third input signal, QEPI, can be used to reset CNT.PC.
QDEC can count the total number of revolutions. A top value of CNT.PC is written to the Position
Counter Top Value in the Top Value register (TOP.PCTOP). When CNT.PC counts up to this
value, it wraps around to zero and the Revolution Counter field (CNT.RC) is incremented.
CNT.RC is decremented when CNT.PC counts down and crosses the zero value. CNT.PC will
then be reset to the value in TOP.PCTOP.
Handles three input channels:
Optional digital filter on inputs
16-bit position counter and 16-bit revolution counter
32-bit timer/counter mode
Software trigger or peripheral event trigger
Compare function with peripheral event generation
Capture function on peripheral event
– Two phase signals (QEPA, QEPB)
– One index pulse (QEPI)
QEPA
QEPB
QEPI
AT32UC3C
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