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Thread: Power both Teensy 3.2 and Octo board

  1. #1
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    Power both Teensy 3.2 and Octo board

    Hi guys,

    For a permanent light art installation I am using Teensy 3.2 and 6 60led led strips.

    I have a teensy 3.2 with an octo board soldered on it. I have cut the connection for usb power, so the Teensy should only get power from the external PSU. When I power only the octoboard the Teensy is not powered. Therefor I connected also 5v power to the teensy and now everything works fine.

    Is this a goog solution, powering both the octoboard (5v and GND and the Teensy (a14/DAC and GND)with 5v and ground cable? Or wil this malfunction after some time?

    Best, Rob

  2. #2
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    I'm pretty sure powering the octoboard at 5v & gnd connection should power the teensy 3.2 through vin.
    If it doesn't you've blown up the teensy 3.3v regulator. Are you saying you are putting 5V on pin A14 and the teensy is working?

    I'll wait to see someone explain how that is working but I would be interested if you could measure the 3.3v line and tell me what your getting.

    I'm gunna say not a reliable setup.

  3. #3
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    Quote Originally Posted by Gibbedy View Post
    I'm pretty sure powering the octoboard at 5v & gnd connection should power the teensy 3.2 through vin.
    If it doesn't you've blown up the teensy 3.3v regulator. Are you saying you are putting 5V on pin A14 and the teensy is working?

    I'll wait to see someone explain how that is working but I would be interested if you could measure the 3.3v line and tell me what your getting.

    I'm gunna say not a reliable setup.

    See attachment for my set up.

    I get 4v from the 3.3v pin (the pin in between GND and VBat)

    Without this my Teensy board dus not power up and does not receive power from the Octoboard. I cut the line between VIN and VUSB.


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  4. #4
    Senior Member PaulS's Avatar
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    Gibbedy is right, when you power the Octoboard, the Teensy board should be powered over the Vin pin.
    Something is definitely wrong; you should read ~3V3 on the 3V3 pin. Don't power the Teensy on pin A14/DAC please.

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    Paul

  5. #5
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    Quote Originally Posted by PaulS View Post
    Gibbedy is right, when you power the Octoboard, the Teensy board should be powered over the Vin pin.
    Something is definitely wrong; you should read ~3V3 on the 3V3 pin. Don't power the Teensy on pin A14/DAC please.

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    Paul
    Hi Paul,

    Thanks for your reply. I checked the power on the 3.3v pin according to Gibbedy's request. Why is the teensy not powered by the Octoboard? I get 0V when I check the GND and Vin pins on the Teensy, but 5V when I check the GND and 5v pins on the Otoboard. Do I need to wire the Teensy also to the Vpin and ground pin? That means these pins (on the teensy) are connected to the octoboard on one side and to the external power via a wire on the other side.

  6. #6
    Senior Member PaulS's Avatar
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    Did you solder *ALL* the Teensy pins on the back of the Octoboard?
    If you power the Octoboard with the red [+5V] and white [GND] wire, you should see that +5V also on the Teensy pin Vin. If not check you soldering.

    Paul

  7. #7
    Senior Member PaulS's Avatar
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    After soldering, using an ohmmeter, you should measure less then 1 ohm between the indicated pins:

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    Paul

  8. #8
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    Cutting vin-vusb connection stops your board being powered up through the usb plug. Vin still works as normal. That is you put 3.6-6v on it and your teensy gets supplies with 3.3vdc through its onboard regulator.

    I do t know the electronics, but youíve found that putting 5v on A14 pulls the 3.3v line up through some resistance on that pin. Lucky itís working but can I ask... did you try vin directly before jumping to a14? If you did and you get no 3.3v on the 3.3v pin your regulator is fried.
    Run an external 3.3v regulator is the solution to that.

  9. #9
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    Hey guys,

    I am back on this issue after some time. I have had a lot of difficulties with external power on the Teensy 3.2 and I have lost already 5 of them, each with an Octo board. Everything seems to work fine but after a while the Teensy dies. At first I thought it had to do with bad soldering so I asked help for that. With nice soldering the problem still occurs.

    I am powering my Teensy only through the octoboard, I have cut the vin-vusb connection. I am using this power source, 5V 12A.

    I have 6 strings of 60 WS2812B RGB led strips. I have cut and rewired each led strip in parts of 6-10 leds.

    I am now looking into shottky diodes. I have bought 5A 200V Shottky diodes, and I am placing them in between the power and the led strips. I will also read more topics in this forum to find other solutions, any help is most appreciated. I will update my progress later today.

    Best, Rob

  10. #10
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    Send some pics of your setup and maybe someone will spot something.

  11. #11
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    Quote Originally Posted by Gibbedy View Post
    Send some pics of your setup and maybe someone will spot something.
    as requested

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    please ask if other photos are required. The LED strips are made in China, somehow the + and - are switched ).

  12. #12
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    So your led strips go into a terminal strip.
    From there they head off in two Ethernet cables to your teensy. Take a picture of where the red and white wire goes.

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  14. #14
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    Looks ok to me. I suppose your power supply could be really bad like your already thinking. I donít think Iíve managed to blow a teensy up so something is off.

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    Hi Gibbedy, thanks for your help so far. The strange thing is that it occurs with other identical power supplies as well. I have four of these and previous Teensyís died also on one of the other power supplies. Can i put a 1A Shottky in between the Teensy amd the power supply for protection, or perhaps a 5V regulator?

  16. #16
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    Protection from reverse voltage? Yeah. Maybe itís a voltage spike. If it were my project, and I had blown up 5 teensyís, I would run a seperate 5 v supply (only connecting gnd between the supplies. I would use a usb phone charger or something and cut up a USB cable as it would be available. Then if you blow it up you know itís something else. Maybe you generate allot of static or something.

  17. #17
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    Sounds like a plan. A few questions left. Do I need to connect the ground of each power supply? Currently i am using two identical 12A power supplies which I havenít connected through ground so far.

    I can use a cut up usb cable, how do I connect that to the octoboard?

  18. #18
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    If your lights work then they are connected. Maybe in a way you donít see but thatís the way it is. Are your teensyís blowing up in this configuration your describing now or the one you took a photo off.
    ?

  19. #19
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    Hi Gibbedy,

    After a busy period finishing the art installations I wanted to let you know that thanks to your suggestions I solved my issue with frying my Teensy's. At the end I connected the grounds of both power supplies and that did it. No more Teensy's died since then so excellent work, thanks a lot!

    Best, Rob

  20. #20
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    Thanks. So ground was connected only through supply mains earth before. Someone smarter than me could post a circuit diagram of what could have happened in this scenario but Iím happy to hear the result.

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