How to Troubleshoot Pedal Pi

6 years 8 months ago #965 by Ray
Replied by Ray on topic Build Problem
Its good if you have the chance to learn how to use an oscilloscope, etc.

Basically the best way is to inject a sinewave into the pedal, I use a mobile phone app for this, and just follow the signal going through all the components to tha ADC.
For the output stage you should see two pwms signals 3.3vpp and around 100KHz going out GPIO 13 and 18.

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6 years 8 months ago #966 by beto
Replied by beto on topic Build Problem
It sounds like you've planned my weekend for me. :) I will definitely get back with an update once I unbox this thing and try it out.

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6 years 8 months ago - 6 years 8 months ago #968 by beto
Replied by beto on topic Build Problem
So here is the update. Having 2 separate Pi's (now), I discovered that regardless of the software image I used, there was always a discernible waveform when running the signal generator on the unadulterated PI. The PI with the header socket mounted to is (which has been my only PI until today), did not have a waveform that looked remotely structured.

Any thing you can recommend before I try and remove the darn header socket? Any suggestions on the *best* way to desolder one of these things from the PI?

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6 years 8 months ago - 6 years 8 months ago #969 by Ray
Replied by Ray on topic Build Problem

So here is the update. Having 2 separate Pi's (now), I discovered that regardless of the software image I used, there was always a discernible waveform when running the signal generator on the unadulterated PI. The PI with the header socket mounted to is (which has been my only PI until today), did not have a waveform that looked remotely structured.


So to be clear, you mean that:
  • When loading the signal generator in a "clean" Pi-Zero you you have PWM signals on GPIO13 and GPIO18
  • When you connect the Pi-Zero to the Pedal-Pi, BOTH signals disappear
Is that what you mean?

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6 years 8 months ago #971 by beto
Replied by beto on topic Build Problem
Again - thanks so much for the support.

Major update. To answer your question, I didn't have either attached to the Pedal PI. I was running them unattached. The PI that had the header socked installed was not functioning. So I started to unsolder the header. This turned out to be a pain. I stopped. And just for fun, I plugged it back in. This time, the signal generator worked and output to the Pedal PI. But the input did not. So I resoldered the SPI interfaces.....and SURPRISE! It passed audio through.

Now, that's the good news. The next part is my next issue.

There seems to be a weird distortion after playing a few seconds on the tremolo. It plays fine, then gets distorted, then gets fine again.
There seems to be a weird pitch shifting with the delay (and the distortion mentioned above).
There also seems to be a weird pitch shifting with the bit crusher (and the distortion mentioned above).

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6 years 7 months ago #973 by Ray
Replied by Ray on topic Build Problem
Nice to see that things are moving, seems that you had a dry join, we talk about them in the How to Troubleshoot Guide:
"Check any short circuit between nearby pads and check that all solder points are good. To try to avoid dry joins, please re-solder all the pins again for just a second."
The best way is to re-solder all the joints again, just in case....

There seems to be a weird distortion after playing a few seconds on the tremolo. It plays fine, then gets distorted, then gets fine again.
There seems to be a weird pitch shifting with the delay (and the distortion mentioned above).
There also seems to be a weird pitch shifting with the bit crusher (and the distortion mentioned above).


Seems like you have the wifi enabled... if affects a lot the sound, have a look at this:
www.electrosmash.com/forum/pedal-pi/227-...-in-pedal-pi?lang=en
Probably a ifconfig wlan0 down from a parallel terminal will fix it.

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6 years 7 months ago #977 by beto
Replied by beto on topic Build Problem
Sadly, this did not - but at the very least I am in a semi-working configuration now. I can troubleshoot a lot more effectively now that I have output. Thanks again for all of the assistance. If anything else comes to mind as to what the source of the distortion is (by the way, it is periodic and comes and goes at regular intervals), please let me know.

Best Regards

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6 years 7 months ago #980 by Ray
Replied by Ray on topic Build Problem
The pitch shift (specially if you play the wave generator) is always related with software, when is slowed by any factor results in a variable execution time/pith shift.
Try to make sure that you dont have any printf in the code, and you have all working smooth without wlan, displays or processes that slow the execution time.

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6 years 7 months ago #994 by BM
Replied by BM on topic How to Troubleshoot Pedal Pi
So I just got my pedal pi together and the voltages test ok, however I am completely new to raspberry pi, and C for that matter. I've done a little bit of Unix a long time ago making a hackintosh. I can't seem to get the libraries connected right.. I am using a Pi 0 W if that makes any difference. My soldering job on the 40 pins is the only thing I'm a little worried aobut, But I figured hey it turns on. So I've just been trying to test a program and have tried the triangle generator and hardware detect over and over. Sorry I'm a total noob. imgur.com/a/GEeuL


Attachments:

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6 years 7 months ago #995 by Ray
Replied by Ray on topic How to Troubleshoot Pedal Pi

Rendering Error in layout Message/Item: array_keys(): Argument #1 ($array) must be of type array, null given. Please enable debug mode for more information.

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