Are my wheel encoders working?

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1

I recently bought this encoder product. https://www.pololu.com/catalog/product/1218 I have been struggling with ever since purchase. I have gone through all the information I can find on using them both with and without interrupts but am not making any headway. I have tried them on both Arduino UNO and DUE and cannot get consistent signals from the wheels. I am beginning to worry that the encoders themselves are not working. Is there a way to test them? I do not have an oscilloscope.

Thanks in advance for your help.

2

Surely you have a multimeter. While the encoder is powered up, use your multimeter on the voltage range to check whether the OutA and OutB signals alternate between high and low as you very slowly rotate the wheels. If you do not have a multimeter, now is the time to go out and buy one.

Note: if you are using the encoder with Vcc = 3.3 V, have you calibrated the output as described under “Modifying the Encoder for 3.3 V Operation” on the product page? Again, your multimeter will come in handy for this.

3

I hooked OutA and OutB to a multimeter and rolled the wheel slowly and did not get reliable variation in voltage. For a short time I had the OutA falling from roughly 5 volts to zero once a rotation but otherwise nothing. The encoders are powered by 5 volts from the Arduino UNO.

Any other suggestion?

4

Did you measure the voltage between OutA and OutB outputs as your post suggests, or did you measure the voltages from OutA to ground and OutB to ground? In any case, you should see a number of transitions (12 “highs” on each output) per wheel rotation. If not then the encoder may not be functioning correctly.

5

I measured the voltage between OutA and OutB to ground. That is correct isn’t it?

If the encoders are bad and assuming I received functioning units, what is the most likely cause of failure?

6

Hello.

Could you post pictures of your setup, including the soldering and all connections?

Also, did you turn the potentiometers on the board? If you have not, please do not do it now, as this will throw off the calibration.

-Brandon

7

Here the setup I am using for testing. 5V is coming from the Arduino UNO and I am measuring the voltage between OUTA and ground. As I turn the wheel the voltage stays constant as shown.

photo.JPG1035×1205 392 KB

8

BTW, I did not touch the pots.

9

It looks like you have the encoder’s Vcc pin connected to the Arduino’s Vin pin (instead of the regulated 5V output). Have you ever powered the Uno through the power jack or Vin pin while it was in this setup? If you have, the encoder might have already been damaged.

-Brandon

10

Thanks, Brandon. I connected the encoder’s Vcc pin to the Arduino’s 5V pin and I am now getting voltages falling to roughly zero at reproducible points in the wheel’s rotation out of both OUTA and OUTB. Maybe I’ll get these things to work afterall! I appreciate the help.