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This seems likely! From the error it looks like we’re calling the teensy-variable-playback library, and `playWav` takes a `const char*` filename. So I’d try this for a start (convert the `String` to a C-style char array): playSdWav1.playWav(filenames[fileCount].c_str())

Thanks @defragster and others for this thread! It helped me get per-unit serial number working on my drum machine, and I learned a lot. Just posted it on my blog: Setting Teensy USB descriptors at runtime. I only covered my specific use case, but linked back here so people can dig into the details.

Love that idea! Good-looking build too. 😻

Well I’m sure the current limiting resistor is a good idea, but it turns out that wasn’t the problem. The distortion is still there. But I have made some progress: I tried feeding in audio from an external source instead of the analog drums and when the beat is running I still hear the...

Ok. Thanks for clarifying! I guess I’ll revert to the theory that I blew up the audio board by omitting the current limiting resistor. I’ll try building another one with the additional resistor/cap and see how it goes.

Right! I was thinking I could use the other side of the TL072 to centre the audio signal around 1.65V like this: But I think there’s a hole in my understanding: if the audio board has a capacitor between the line in pin and the SGTL5000 that removes the DC component, the ADC won’t see the bias...

Thanks @MarkT! Here’s the relevant part of my circuit as it stands: Since I only added the series resistor after testing it without I may well have blown the Teensy Audio board – I’ll try rebuilding the circuit with a new one and see if the extra protection helps. But first I’d like to make...

I’m working on a drum machine where the Teensy is triggering analog drum circuits, then the audio is fed into the Teensy (audio board line in) for processing. The drums with big transients are distorting. I simplified the audio code to route the input directly to the output, and recorded the...

I replaced the teensy_serialmon script in /Applications/Teensyduino.app/Contents/Java/hardware/tools/ with the version you posted and so far have seen no crashes! I’ve tried keeping the Serial Monitor open in Teensyduino while building and uploading sketches to the Teensy, running the serialmon...

✋ I’m watching! I should be able to test this out later this week. Thanks for looking into it, Paul.

Great! I’m glad it wasn’t just me making a stupid mistake in my code. :)

Ok, I’ve eliminated almost every cause I can think of now... I can reliably reproduce the bug and here’s all the info that might be of interest: MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports) 2.3 GHz Dual-Core Intel Core i5 processor Brand new Teensy 4.0 connected to one of the...

I reproduced the crash with this version of serialmon, but the crash report looks very similar: panic(cpu 3 caller 0xffffff80033c5396): Kernel trap at 0xffffff8003856f73, type 14=page fault, registers: CR0: 0x0000000080010033, CR2: 0x0000000000000018, CR3: 0x00000002672bf15b, CR4...

A quick update: I’ve eliminated a few possible causes, but haven’t narrowed it down to a reproducible set of conditions yet. The USB-C hub was not the problem. The crash still happens when the Teensy is the only USB device connected to the MacBook Pro (using a single Apple USB-C to USB-A...

I’ve been seeing this for several months now too, using the latest platformio (currently 5.2.3) and a Teensy 4.0 (I’ve tried several different brand new Teensy 4.0 boards). If I run the platformio build command to upload new code to the Teensy while serialmon is running, 50% of the time I get...

I’m seeing this intermittently too. I’ve tried to isolate the problem by trying various combinations of hardware/software sequences when uploading new code to the Teensy, but without much success. Keeping an eye on this thread!

Easy as that, eh? Hats off to you, sir. :) I’ll go with a decent 9V PSU for now and iron out the finer audio details then see how much more energy I have for power supply design. Thanks everyone for the help! I’ve learned a lot. I’ll post some details of the project once it’s up and running.

Swapping the power supply for a better one (a Korg 9V PSU instead of a random cheapo) eliminates almost all of the noise. Gah. If I wanted to make the circuit more resilient to cheapo power supplies by adding some filtering/isolation, is there a standard design to start with? @Blackaddr the...

@fdaniels good question! I had tried that a while back, but not recently. Running the circuit from a 9V does indeed eliminate the noise. So... I need to filter the power supply?

I came across this post that sounds like a very similar problem to mine, and it made me wonder whether my skimpy breadboard cables were not giving me a clear enough ground connection. I swapped all the ground wires out for thicker wires soldered to the pins and it did reduce the general noise...

The JFET buffer is quite common in guitar pedals (this sort of thing), but a TL07x buffer makes sense too (and should be better quality). I’ve swapped the buffers out for TL071s – they work fine but the noise is still the same. That would definitely simplify things, but the hardware delay is...

@fdaniels thanks for the pointer on the inductor position – I think I misunderstood your earlier recommendation. This makes much more sense. Here’s the full circuit that I’m tinkering with. One of the Teensy outputs is fed through a delay circuit (with the delay controlled by the Teensy using a...

Quick experiment – I don’t think this is the correct approach, but it does eliminate the noise and maybe that would be helpful in diagnosing the problem. I grounded the mixer to the Teensy audio board’s line out ground pin (AGND in the diagram) and most of the noise disappeared. I guess this...

I’ve made some progress! A few steps forward, a few steps back. I bought some 33uH inductors and added them to the circuit as @fdaniels suggested. They reduced the power supply whine a little. Then I did a lot of reading and checked out various teensy DAC schematics. I can see that (as...

@jonr @fdaniels @MarkT @Blackaddr thanks for the tips! That all makes a lot of sense. I’ll make some tweaks to the circuit and see how I get on.

I’ve been working on a Teensy 4.0-based music machine for a while, and I’m getting down to the last niggly noise issues. I’m hoping this is something people have solved before, but I haven’t managed to find any Teensy-specific tips on the forum. I’m using the audio shield and the audio library...

Adding AudioNoInterrupts() around the stop() calls in my sketch makes no difference – the play() calls still sporadically fail (with or without a delay() between the stop() and the play()). This is my working version – no stop() or delay() calls, just wrapping the play() with...

After a lot of experimentation and digging I came across this in the Audio library source code: // When changing multiple audio object settings that must update at // the same time, these functions allow the audio library interrupt // to be disabled. For example, you may wish to begin playing...

Thanks, Pete. I tried adding the delay (and a longer delay just in case) but it had no effect. Keep the suggestions coming! In the meantime I’m going to try adding some debug logging to the Audio library to see if I can figure out exactly where and why it’s failing.

I ran the SdCartTest sketch to check whether it was just a case of the SD reads being slow or inconsistent, but the results were (I think) totally fine. I consistently got values close to: Reading LOOP1.RAW, LOOP2.RAW, LOOP3.RAW, LOOP4.RAW: Overall speed = 1.33 Mbyte/sec Worst block time =...

Thanks, Pete. I tried this but it doesn’t make a difference. And in fact it looks like the play() function already calls stop() itself: https://github.com/PaulStoffregen/Audio/blob/master/play_sd_raw.cpp#L42 I’m starting to think it might be a hardware issue. My soldering is not amazing and I...

I’ve wired up a Teensy 4.0 with two Audio boards for the quad output setup with a 32GB SanDisk Ultra SD card and it’s working splendidly. This forum (especially https://forum.pjrc.com/threads/61123-Teensy-4-1-and-4-channel-audio-(AudioInputI2SQuad) ) was a goldmine of useful info. But now I’ve...