Teensy2++ Not Recognized by PC

[VictoryNeal]

Hi,

The Teensy 2++ was recognized by PC before, but today it is not. It doesn't run the program when I press the button. There is power (5V) detected from the Teensy board, which means the connection should be fine. When I unpluged and pluged the USB cable, there is no sound heard from computer, but there was sound before to show the PC detects a new device. I tried different good USB ports but the teensy is still not detected (I used mouse to test). I shut down and reboot the computer. They all didn't solve the problem. Any other advice?

Best

[VictoryNeal]

To add more details. I used Windows10. I tried to upload the Blink example, it shows

Binary sketch size: 2,750 bytes (of a 130,048 byte maximum)
Estimated memory use: 24 bytes (of a 8,192 byte maximum)
Teensy did not respond to a USB-based request to automatically reboot.
Please press the PROGRAM MODE BUTTON on your Teensy to upload your sketch.

Then I pressed the button, no response.

[joepasquariello]

To add more details. I used Windows10. I tried to upload the Blink example, it shows

Binary sketch size: 2,750 bytes (of a 130,048 byte maximum)
Estimated memory use: 24 bytes (of a 8,192 byte maximum)
Teensy did not respond to a USB-based request to automatically reboot.
Please press the PROGRAM MODE BUTTON on your Teensy to upload your sketch.

Then I pressed the button, no response.

A common issue is the USB cable is a power-only cable, as opposed to a cable that supports both power and commuication. If you have another cable, try it.

[VictoryNeal]

As I said in the first post, the same setup works before, so I am sure the cable communicates. Thanks anyway.

[PaulStoffregen]

Is it a genuine Teensy or a counterfeit? If unsure, can you show us photos?

Sadly, for these very old models there are a lot of counterfeits out there.

[VictoryNeal]

This teensy2++ worked well before, but are not recognized by PC today, so it cannot be genuine before and turn to fake today, right? By the way, I have went through other similar posts and tried many different methods to test where things go wrong. Are there advice not mentioned too much in other similar posts? I doubt my teensy 2++ die. How to make sure of it?

[KurtE]

This teensy2++ worked well before, but are not recognized by PC today, so it cannot be genuine before and turn to fake today, right? By the way, I have went through other similar posts and tried many different methods to test where things go wrong. Are there advice not mentioned too much in other similar posts? I doubt my teensy 2++ die. How to make sure of it?

It actually could work before and still be counterfeit. ...

Things to check include stuff up at: https://www.pjrc.com/teensy/troubleshoot.html

I don't have any of these boards, so cannot help much. Sometimes with other boards, your USB setup become such that the board cannot fully connect.
So one of the first things, I would try if it were my board.

Try to reprogram it with simple blink sketch or the like. I would try steps of
a) try to simply upload command in Arduino and see if it completes the update and the led blinks.
b) if not, try pressing the program button.
c) Try holding the program button on when plugging it in and then try to program.

If still nothing, would check things like, if you measure resistence between +5v and GND and see if any dead short.

I would try changing USB cable. I have had cables that just stopped working with a particular teesny

[VictoryNeal]

Hi KurtE,

Thanks for your advice. I will measure resistance between power and ground. Others have been tried, but maybe I will try multiple times. Any idea what may damage the teensy?

Best

[defragster]

A photo, if possible, would rule out a counterfeit. The counterfeit units may work at first - but they do not have the robust brickproof certainty of a PJRC Teensy.

[PaulStoffregen]

Any idea what may damage the teensy?

The most common cause of death is accidentally driving the power and any signal pin above the power supply voltage, or with a negative voltage. The old 2.0 boards ran on 5V, so usually this only can happen when connected to other circuitry which has its own power supply.

May or may not apply to your situation.

This is for genuine Teensy. Counterfeits have been known to be killed (or get stuck unable to go into bootloader mode) by certain programs which use sleep modes or configure slower clock speeds. Again, may or may not apply.

[VictoryNeal]

Sure, I will send a picture tomorrow, but it looks the same as that on the official website, at least from the top view. I don't know how to tell truth. By the way, there is no stock on official website. Where to buy more?

How to save it if stuck?

[VictoryNeal]

The 5V pin and GND are disconnected.

[PaulStoffregen]

That sure looks like a genuine Teensy++ 2.0.

[VictoryNeal]

That sure looks like a genuine Teensy++ 2.0.

So what's next?

[VictoryNeal]

Any ideas about how to test what's going wrong?

I have extra new Teensy ++2 which could be detected by PC. However the not-detected Teensy is soldered on board, so it will be a pain if de-solder and replace the new one. What's worse, I don't even know how and why it died, so it would be much possible that the new-solder teensy would die soon too.

Any recommendations about substitution of Teensy ++2?

[defragster]

Has the Teensy ++2 been programmed one or more times since soldering and this failure? Was it working before soldering?

[VictoryNeal]

It worked before and after soldering. I also programed it for many times before and after soldering. Would it be possible that programming will damage it, since I programed it for dozens of times?

[KurtE]

Most of these chips have a maximum number of times an area can be written to. But I have not seen any that were in the dozens of times.
I believe more like in the range of 100 thousand times.

BUT if your programming of the board went bad and the USB data is screwed up, then things can interfere with the PC seeing the board.
I have not played with T2 for a very long time and only for a bit.

With T3.x/T4.x, this is where, plugging it in while holding the program button, could hopefully then bypass the main chip running.

Sorry again, my memory on using these is rusty at best. So for example, I don't remember if these chips ship with some form of bootloader?
And if they could be corrupt. I know with some other AVR boards I have used, I would sometimes overwrite the bootloader, when I was using a hardware debugger,
and when I wished for the standard Arduino setup to work I would then need to reburn in the bootloader.

But again I don't know if this applies here or not.

[PaulStoffregen]

Would it be possible that programming will damage it, since I programed it for dozens of times?

The flash memory will gradually wear out if repetitively programmed, but the endurance should be at least 100,000 erase/write cycles.



Many people have put these claims to the test over the years. Usually the finding has been that these sorts of specs are very conservative, with actual failure (running at room temperature) often 10X to 20X the minimum endurance claimed.

[PaulStoffregen]

The main question at this point is whether the hardware is damaged. Usually the main thing that destroys chips is driving the power supply or other pins too high, or with a negative voltage.

But there are many other ways to stress the hardware, which often do not result in immediate failure, but can damage the chip. Shorting the pins to GND or 5V and attempting drive the pin to the opposite logic level can cause excessive current flow. From your other thread, looks pretty likely that happened at some point. Whether that killed your chip, I don't know. It certainly isn't good and can impact the long-term reliability. I can tell you I've personally made that mistake many times while experimenting and rarely does the hardware die immediately, even though the pin's current goes far beyond the rated specs.

Anyway, the very first thing to do is try to establish if the hardware is destroyed. Assuming you have good 5V power, and if it's not showing any signs of running whatever you previously programmed, and pressing the pushbutton doesn't give any response in the Teensy Loader window, I'm afraid the signs aren't good.

One final test to try is fresh reboot of your PC without the harwdware connected and then hold the pushbutton down while you plug in the USB cable. Get Teensy Loader on your screen before you plug in the cable, and make sure Auto mode is turned off (so you can easily see if the hardware gets detected). It's a long-shot, and usually that last resort test made a difference in the times before Microsoft finally published good USB drivers in Windows 10. But it is one last thing to try.

And I know you said in msg #4 that you're sure your USB cable is good. But I'm going to bring it up again, because sometimes after a lot of troubleshooting effort the problem does in the end turn out to be a low quality USB cable. (and unlike flash memory which is rated for 100,000 cycles, good quality USB cables are rated for 5000 insertion cycles and cheap ones probably survive much less)

But in the end, if the hardware really is dead, there's simply not much point in spending a lot more time troubleshooting. There is no practical way to fix a chip that's been internally damaged.

Sadly, Teensy++ 2.0 was discontinued earlier this year, partly because it's very old, partly because sales on those old models slowed to a trickle over the last few years, but mostly because the chips aren't really available anymore. Tinkersphere might still have some but at an outrageous price. Before you go that path, maybe start a new thread and ask if anyone on this forum still has an extra they might be willing to sell.

Wish I had better news or a magic solution, but sadly this is the best I can do.

[VictoryNeal]

Hi all,

I changed the Teensy and everything is working. Here are some catch-up questions or consultations to make this Teensy last longer. A kind reminder: Teensy2++, Win10. In my case, there is only one program I need Teensy running when I am doing experiments.

After finishing experiments, should I unplug the USB cable directly while PC is on? Is it OK if I keep the USB cable connected and put PC at sleeping mode? Since I only need one program, the button on Teensy won't be used usually, right?

[VictoryNeal]

To make Teensy2++ last longer, should I unplug it every time after experiment? Is it OK to unplug while the programing is running? Should I put PC at sleep mode when not using and leave Teensy connected?

[VictoryNeal]

Any ideas?