VUSB Low voltage problem

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Redcat101

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Hello all,

Not my first project, but my first post!

I am building a USB controller for Elite:Dangerous again, using a Teensy 3.2 and some illuminated buttons.
The first one i made was a grand success given the fact id never built a thing like that.
Now the next ones are beeing built, (2 of the same, one for me, one for my wingman) and testing is very positive up until now.

But today, suddenly, it seems the Teensy decided it needed a break, and possibly broke.

I have connected the pushbuttons into a matrix using ports 17-18 for columns, and 0-1-2-3-4-5 for the rows.
Then i have a Step-up-module connectec to AGND and VUSB ports, which power the LED's in the pushbuttons.
On port 0 i put a resistor because otherwise the matrix disbehaves.
This whole setup is still working after 2 years in my original controller and seemed to work in the new one while testing.

Same usb cable in the Teensy, same port on laptop, but now, when i plug in the controller, the pushbuttons light up for a few seconds, then the LED's start to dim until the eventually go out after a few more seconds.

Time to measure:
The cable is supplying a steady 5-ish volts, but measuring VUSB and AGND, i only measure 1.6V // on GND and the 3.3V, i only measure about 0.06V


Long story short: is the Teensy dead/dying, or just trying to wind me up? (that last one was retorical cause it winds me up.. it worked fine, now it doesnt)

Since this im building 2 of these, it was already annoying one Teensy was DOA, so id be pretty puzzled if this one just died on me too.
It doesnt register in the list of USB controllers in windows and doesnt make the "USB connected" sound. The new Teensy i just unpacked and programmed does..


Please does anyone have an idea?

Id be ok with it IF i have a dead Teensy but i dont wan to repeat this when i again order a new one


Many thanks in advance!
(i searched the forum but couldnt find a similair post)
 
What between VUSB and GND? If you find 5V there, you grilled the inductor between GND and AGND. If you can't find your 5V there, too, check the soldering of the USB connector. These may break when often plugged/unplugged.

If the inductor between AGND and GND is broken, that explains why one should not draw lots of current from the AGND pin. It is thought as clean reference potential for DAC and ADCs, not as a supply pin. Thus, please change your future layout in ever case to feed the step-up converter, connect it between VUSB and GND!!!

No extra cheese. I'm in a rather aggressive mood since I quit smoking... ;)
 
Redcat101 said:
The cable is supplying a steady 5-ish volts, but measuring VUSB and AGND, i only measure 1.6V // on GND and the 3.3V, i only measure about 0.06V

Long story short: is the Teensy dead/dying
Click to expand...

0.06V between 3.3V and GND sounds like something is shorting out the 3.3V power line. Whether it's on Teensy or somewhere in the stuff you've connected is a good question. The answer can be easy if you put Teensy into a socket. Just unplug and check whether the 3.3V power is good when not plugged into the rest of your wiring. If it's hard soldered in place, then things are much harder to troubleshoot. If your multimeter has a good millivolt mode, maybe you can see 0.05 or even less voltage when you measure with the 2 leads "close" to the problem, and maybe more than 0.06V when you're physically farther way from whatever is causing the short.

Usually with either separating stuff and testing each part, or by hunting around the board with sensitive mV measurements you can answer the "what" question of the failure. Answering "why" can be much harder...
 
First off, thanks for taking the time to reply!

i also quit smoking recently so i know what you mean ;)

I will look into this!
I did have another teensy so i uploaded the code and tested it, worked.
Then replaced the nonresponsive in my controller with the new one, then that didnt work..

Its so weird.. im using the excact same layout/design as the first controller i made which is still working great today..

The things that are different this time are

-Less buttons
-Better soldering skills :)

Ive connected the first teensy the first time and havent taken out the usb connector, as i dont like to wear out the port on the teensy
This thing worked and i was so glad, but then a few days later i connected it back into the laptop and then it was doing this weird stuff..
The lights go on, then they dim. Then go off all together..

The new teensy worked fine, then didnt..
I just dont know why, i checked the soldering which is (sorry to say) quite nice..
The wires are what i took from work, 0.5 Halogenfree Studercable, so good stuff really.. on the 'old' one i just took wire out of an extension cord

Im thinking is it because this controller has less buttons and maybe i needed a higher value resistor in there?

The 220 Ohm resistor is on port 0, like in the other controller

attached is a layout of the thing, i cant for some reason upload the Fritzing file itself but i can provide it elsewhere if needed

24 and 25 are the rows, 0 trough 5 are the columns

layout final.PNG
 
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