[SOLVED] How to detect direction of a rotary encoder?

[hafrse]

Need some advice on how to build a circuit that generates short to GND only when the encoder is rotated clockwise by using the CLK and DT outputs, the square wave pluses generated from the encoder will be feed into a pitch control circuit (Pitch CLK P1.jpg) together with the grounded detection when the encoder is rotated clockwise (Pitch DIR P2.JPG)

Thanks!

 

[danadakk]

https://www.ti.com/lit/ug/tiduaa8/tiduaa8.pdf?ts=1666319019907

https://www.ti.com/content/dam/videos/external-videos/en-us/9/3816841626001/6308652805112.mp4/subassets/interfacing_with_quadrature_encoders_-_updated.pdf

Tons of videos on youtube.

Todays processors typically have a quaddec component on them for that purpose.

https://www.infineon.com/dgdl/Infineon-CE195354_PSoC4_Quadrature_Decoder-Code%20Example-v01_00-EN.pdf?fileId=8ac78c8c7d0d8da4017d0e7212ac0506

Regards, Dana.

 

[hafrse]

https://www.ti.com/lit/ug/tiduaa8/tiduaa8.pdf?ts=1666319019907

https://www.ti.com/content/dam/videos/external-videos/en-us/9/3816841626001/6308652805112.mp4/subassets/interfacing_with_quadrature_encoders_-_updated.pdf

Tons of videos on youtube.

Todays processors typically have a quaddec component on them for that purpose.

https://www.infineon.com/dgdl/Infineon-CE195354_PSoC4_Quadrature_Decoder-Code%20Example-v01_00-EN.pdf?fileId=8ac78c8c7d0d8da4017d0e7212ac0506

Regards, Dana.

The inputs I have in this vintage device (tape recorder) is Direction detect (Ground when the encoder is rotated clockwise) and clock input (please see the previous images)

--- Updated Apr 23, 2025 ---

May be the Pitch Direction is actually to be connected to the DT output of the encoder. Will try that tomorrow

 

[BigBoss]

There should be a 90-degree phase difference between CLK and CLKBAR signals in Optical decoders. Leading Phase or Lagging Phase give Rotation Direction.

 

[BradtheRad]

Sounds like you obtain digital output... Yet maybe if you convert to an analog waveform, here's a dirt-simple rising-falling detector to tell you what direction it's going. Values need adjusting to desired response.

--- Updated Apr 24, 2025 ---

Link runs my schematic in Falstad's animated interactive simulator:

tinyurl.com/2dc56con

 

[hafrse]

Solved, just connected the CLK output to the Pitch CLK input and the DT output to the Direction DET input