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Sadly (and gladly), I have duplicated the problem. I have been "stress testing" Teensy 4.1 units in a female-header-mounted manner (on my customer daughterboard) before soldering them in without the headers. All have run without trouble for at least an hour before use. All have run well after...

I think I see it all in usb_desc.c. I've tried some permutations and so far I either enable or disable both input and output. My test for success it's a zoom session bringing up the audio input and output menu. My device appears in both audio in and audio out or it appears in neither. I could...

Thanks I just posted in that thread to @Jigglypuff

@Jigglypuff were you able to create a USB audio interface that is recognized only as a microphone (input), and not as a speaker (output)? And if so, what is the minimal change to do so? I've looked at usb_audio.h and find this class declared: class AudioInputUSB : public AudioStream but I...

I've been tackling other issues since my last post, but this issue emerged again for a customer. ...with their iPad automatically assuming that my device was an audio output, simultaneously disabling the speakers of the iPad. Swapping that back has proved difficult on the iPad user interface...

My Picoscope 2204A arrived, and I am thrilled! Here are my findings: Probing both old (2023) and new (2025) Teensy that are working, I get a 1MHz oscillation at the probe location noted in the pictures. The New Teensy is the previous failing B model. It often runs after sitting overnight...

Well, that would be frustrating. I'm ordering some 2.2 megaohm resistors in the 0402 size from Digi key. I think I'll be able to test out the resistor theory adequately, but it sounds like if this is a BGA problem, I'm stuck with trying to detect the failures with testing before shipping, and...

Thanks. Picoscope 2000 arriving Tuesday.

@Dogbone06 , did you check the oscillation of the crystal before replacing the resistor? It looks like I'm on the same path. I mentioned you in the other thread. I have two apparently bad off-the-shelf teensy 4.1 units and I discovered the problem after mounting them on my daughterboard. And by...

@jmarsh - Oh, it seems right on target! Thanks @Dogbone06 ! Interestingly, as I brought out my old oscilloscope finding that it is no longer supported on Mac. I do have a Windows box that I can try it. That's not the interesting part… as I was plugging in the failing teensy, it was working! I...

I'm using MIDI and SysEx messages to transfer files and it's going well. Only so many avenues to investigate!

Thanks, @KenHahn I’ll check out the crystal as you specify. If the crystal is not oscillating, what should I assume from that? My design is for space efficiency (it all fits in the palm of your hand). I’ve prototyped a thicker device due to this issue, allowing stacking of boards with...

I tried to squeeze technique on both failing boards, on the RT1062 and on the MKL02. I used plastic spacers and a vice grips with gentle and moderate pressure. No change in the results. As for the crystal, I think you're talking about the one that's on the RT1062. I use an oscilloscope every...

OK, Done with a Dremel. Results: Same behavior from isolated Teensy (2025 model) liberated from the second failing board 1) power on: 4 flash at boot loader 2) 15-second-reset-hold: 45 second solid red followed by 4-flash at boot loader 3) unplug and replug - 4 flash at boot loader. So it...

Progress Report: I took one of the failing soldered-on boards and gave it a good scrubbing on its top side with a toothbrush and 99% IPA. [The alcohol, not the beer :-) ] I also held the board vertically and trickled some IPA across it in the area of the main CPU hoping that the underside...

Thank you both, @BillFM and @KenHahn ! As I look at the soldering on the new and old boards, they do look different, but I don't see any clear cold solder joints. Zoom into the picture on post 12 above and you'll see that the old boards are more Hershey's kiss like and the new boards are a...

I've been shipping a Teensy 4.1-based product mounted on my own board for about 2 years. This latest board, since early this year. No Teensy-relatd problems before these two. On the two problematic boards, I see the code CTQB2503J I have one header-mounted one with this same date code...

I do implement my own firmware flashing code after downloading a hex file (via BLE to the uSD card), using FlasherX. I don't think I had yet done that with these two units. That's usually done in the field in the customers' hands. I also access EEPROM regularly through what I think are the...

Thanks @defragster ! 15 second hold of the reset button does the following: Press and hold reset Press on at 0 0-15 seconds = 4 blink release reset ==> solid red 15-60 seconds = solid red 60....... = 4 blink 10 minutes (or so, on one of the two boards) = 9 blinks documentation here Trying...

I now have my second failing teensy 4.1 mounted. Both blink the same 4-blink pattern on the bootloader-associated red LED. Sometimes they start blinking right away. Other times, it takes a few hours for it to start. When not blinking, my code executes without error. In fact, this second failing...

Thanks @Paul The problem is now intermittent on this one board, and may be related to time-on. Blinking yesterday after being plugged in a while. Unplugged overnight. Working correctly this morning on first plugging in. I'm going to leave it for a few hours to see what happens. Temperature...

@KenHahn , I inspected those areas (24MHz crystal and boo loader) and saw no visible defects. Then I did a scrubbing with a paper towel with some 99% IPA. I even doused it a bit and scrubbed again. It didn't come back alive right away. And now I think that was because it was still perhaps a...

Thanks for that link @KenHahn. So 4 blinks has something to do with: - the 24MHz crystal on the board not oscillating (I can see this and think I could test this)... or - a particular connection between the boot loader chip and the main IMXRT (I would not know how to test this) These are all...

Latest: Problem restarted on its own while sitting on the desk, plugged in. 4-blink red LED near USB persists. I can press and hold reset for 15 seconds (13-17) and the red LED glows for 45 seconds, then returns to 4-blink pattern This on USB C or Micro-USB power with no display plugged in...

yes, on C1 and C2. 4.7K each

Oh my goodness... as I continued testing, I saw the state again...4-flash and otherwise unresponsive. When I unplugged a screen module (in the 1/10th inch header above) the flashing went away and the board booted normally. Plugged the screen back in and it continued to work, and has worked...

I use a standard Teensy 4.1 NE on my own board, connecting D+ and D- with pogo pins so that I can present USB C to the outside. I've shipped over 50 of these without getting this issue. I left the device (a digital trumpet) plugged in to my Mac overnight (I often do) and the app running on the...

I’ve been using platformIO for a few years with different Serial configurations. I’d be happy to execute a test case if you can post a simple codebase that demonstrates the problem

My Mac is now an M4, and the windows box is 2 years old. Building from source, including an installer that does not scare users on Mac or Windows, and a simple UI of each… would be a plus. It’s not a big enough pain point for me to enter the rabbit hole.

I just downloaded those 2023 binaries for Mac and Windows and both worked will for my purposes. The source would need to be compiled with a paid version of QT, would it not?

You guys are great! Thanks so much!

Got it. And nothing magic about 1.000, but rather, getting aware of what measured levels sound good, and what sounds overblown, and adjusting to that?

Thanks, @houtson ! Just what I needed! And the red clipping indicator is shown when you find any peak...read() over 1.0, or 0.9 or some other threshhold? Is that it or is it fuzzier logic?

Thanks, @kd5rxt-mark , that’s a big help! Since I’m blending a few sources, I imagine I’ll connect and monitor a few points along the chain. And the goal is to avoid any point in the chain hitting 1.0, right?

I have this design now, and it's sounding great, through headphones, line-out and USB audio out. I've been winging it in terms of setting levels throughout the chain, trying to intuitively stay below 1.0 at any node. I've have some outlier conditions where I get a hiss. I'd like to rigorously...

I think I'm seeing the light. If anyone is groking this and can confirm or deny assumptions, I'd welcome it: Teensy's USB Audio, when enabled through a define, becomes the equivalent of a stereo USB Microphone and USB headphones When plugged in to a Mac, the Teensy's USB audio IO becomes...

@Math51 , did that solve the problem?

I've done more testing. iPad (9th generation) with iOS 18.1.1 GarageBand USB Camera Adaptor My Teensy 4.1-based MIDI controller With USB_MIDI_SERIAL defined I can send USB MIDI and the GarageBand receives and plays it. With USB_MIDI_AUDIO_SERIAL defined No luck. I've tried these things...

USB C would simplify my designs, and make them more reliable! You know, true pin access (rather than pads) to the D+/D- data connections would be almost as good. Maybe better! I worry about my pogo pins.

I have a JSON config file that could be updated frequently. I mirror the json doc in memory at runtime, and need to push it back to the SD card… either with each little change to configuration, or otherwise require the user to make some explicit Save action. (I could take a time-based approach...

I have a USB audio output at the end of my audio chain (as well as I2S to the SGTL5000) once define in the design tool, and instantiated at the top of my code file, is there any way to disable that USB Audio at runtime, so that it would cease to be seen by a connected USB host as an Audio...

Pinging to restate and update: The immediately-previous post had a critical typo: "Now I can run EITHER GarageBand or LoopBack withOUT fails" That leaves the two of the previous questions, the latter one being more specific: 1) Is there a different name parameter for USB MIDI and USB AUDIO...

I have an update... I thought my testing of LoopBack was without GarageBand in the background. I was in error. Now I can run EITHER GarageBand or LoopBack with fails (so far) but either will fail periodically if the other is running. Even if they are not apparently using the port (no track in...

I've been sending audio MIDI and serial out through USB with this define in PlatformIO build_flags = -D HW_T41 -D USB_MIDI_AUDIO_SERIAL The use of USB audio is new for me. I'm testing with GarageBand, and an audio track and connecting it to "DigiBrass MIDI" audio in port (see question 1). It...

OK, posting here seems as right as anything for FlasherX-related stuff. I've been able to get FlasherX working with little work! I'd welcome input on my assumptions and process. I have a 212K app compiled in VS Code, PlatformIO project running on a Teensy 4.1 In VS Code I added a new...

My code result in 212444 bytes. ~1 second upload. I'm glad because, while I can follow the logic of your custom boot loader logic (mostly), it is well above my pay grade. Thanks for your help!

I’ll check… but since moving from Teensy 32 to 41…. I’ve happily been able to ignore the output. 1-2 seconds to flash over USB with my Mac.

@AndyA can you say more about the embedded boot loader for recovery from failure during FlasherX? All of my devices include USB and the standard Teensy boot loader chip, but I'd love to have a method that's almost foolproof. I've been following FlasherX for a while, and am excited to see that...

Thanks, all, for your replies!

Are there any? I've seen no recent threads about this. Thanks!