Encoder direction problem

[lukebarber]

Hello,

I'm trying to use the Encoder.h library with Teensy. The program compiles without any errors and sort of works but not very reliably. I am using a standard rotary encoder and connecting the output of the encoder directly to pins 7 and 8.

My code monitors the encoder in a loop and does a serial print on whether it is turned clockwise or counter clockwise. So, when I turn the encoder in one direction, it reports the wrong direction about 25% of the time. Has anyone here encountered a similar problem?

Datasheet for the encoder in question is below.

http://www.clrwtr.com/PDF/Accu-Coder/Accu-Coder-Cube-Series-Encoders.pdf

 

[KurtE]

Sorry, I might not be much help here. But might help to know more information like which of their encoders you are using, as it looks like some of them output a single wave and others do quadrature encoding. Also when you are doing this what type of speed are we talking about? (RPM or KHZ).

Which Teensy? Are we talking a 2.0 or 3.2 or 3.5/6? You might also want to do a search on the forum for encoder and see if some of the other threads might give additional hints.

 

[Theremingenieur]

Do you have the open collector or the pull up resistor variant? Did you check with an oscilloscope if the signal levels at pin7 and 8 are clean (no bouncing, quick ramps, full amplitude) ?

 

[PaulStoffregen]

Has anyone here encountered a similar problem?

Yes, many times. It's almost always come down to a hardware issue. Some have been poor connections, others have been encoders with mechanical chatter which require a low-pass filtering with resistors and capacitors.

 

[tni]

Check the pinout. If you have the pins mixed up, you would get the symptoms you are seeing.

EDIT: Actually, that 711 model that you linked to doesn't seem to be a quadrature encoder at all. So the encoder library won't work. That encoder model doesn't seem to be capable of detecting the direction.

 

[Arctic_Eddie]

The data sheet says it's uni-directional. Put meters on both A and A' output and see if they switch in a quadrature fashion. Maybe there's output on only one pin and the other is floating.

 

[PaulStoffregen]

Yeah, for a unidirectional (single pulse, not 2 pulses in quadrature), you could probably just use attachInterrupt and increment a number.

Remember to make the variable volatile type, so the compiler doesn't optimize access to it (by assuming numbers in memory don't change). If using 8 bit Teensy, also disable interrupts when reading anything more than 8 bits.... the usual stuff when moving data from interrupts to your program.