Simple Quadrature Decoder Suits Rotary Encoders

摘要

U2 forms a classic digital "set/reset" logic circuit. Its output (U2, pin 6) will be high or low based upon the phase of the quadrature switch signal (U1, pins 9 and 10) relative to the 1-ms pulse (U1, pin 6). Thus, the output of the "set/reset" circuit (DIR, U2, pin 6) indicates the direction that the rotary encoder is turned. As mentioned previously, each pulse is delayed by the low-pass filter R1 and C1 relative to this direction signal.