Edge count.

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Edge count.

Postby Fat Freddy » Thu Jul 28, 2016 10:14 am

Pico, you read my mind. :D Just what I needed. A couple of weeks earlier would of been perfect.

Had to count each switch of this encoder output and compare to the interrupt output from chip. Several times :shock: .
No doubt I will use it in the future. :lol:

One question though. Why in this attachment. Why does channel 'B' seem unable to carry out an edge count in some area's? - see attached file.

Cheers
FF

Encoder.psdata
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Fat Freddy
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Re: Edge count.

Postby Steve Smith » Thu Jul 28, 2016 2:04 pm

Hello Fat Freddy I hope you are well?

Thank you for your post, I can’t imagine manual pulse counting as I have spent time counting just 20 pulses in your attached file and now my head hurts.

This is an interesting issue you have highlighted as I noticed simply by moving either 1 or the other time rulers the pulse count for channel B becomes populated with the values 557 or 555

I also notice channel A value disappears too and this leads me to think it may be related to noise present on the captured data. (differing noise levels on Channel A and B)

The software is trying to determine the crossing point (Max + Min / 2) and this would somehow appear to be linked with time (Between time rulers)

Applying a 10 kHz low pass filter seems to stabilise the counter between the time rulers but 2 different values are obtained (557 and 555)

Creating a math channel B-2.5 results in similar behaviour.

When generating a pulse signal via an AWG, the edge count is correct between the rulers regardless of the position of those rulers when placed at various points along the prolonged high or low points in the signal.

This again points towards noise as the AWG signal is exceptionally clean.

I will file a bug on this symptom and see how this unfolds.
In an attempt to limit noise could we capture the same signal using the MI007 high impedance probe?

Not sure it will change our symptom but it would assist with the diagnosis

I hope this helps, take care…….Steve
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Re: Edge count.

Postby Fat Freddy » Fri Jul 29, 2016 3:28 am

Thanks for taking the time with that. :D All good here. Still living on my tropical rock dreaming of the day I can drive further than a couple of miles. :lol:

I also got a 555 and a 553 count as well. Neither of these are majors although good to be aware of it but a fix is by far preferable.

In an attempt to limit noise could we capture the same signal using the MI007 high impedance probe?


Now you're just trying to wind me up. :D :lol: :lol: :lol:

The following day after fixing the issue (floating chip pin assigned as a IOC) and assembly, a mounting screw of the circuit board shorted the 5V rail to the 12V. It didn't end well. Total destruction. :cry:
Asides, I don't have a MI007 either.

But you may be on too something. As channel A was an input to the chip and I had put a small capacitor on that circuit. While the output from the chip was just floating.

Thanks for looking and lodging bug.


Cheers
FF
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