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Thread: Power and connection problems teensy to uno serial connection

  1. #1

    Power and connection problems teensy to uno serial connection

    I'm trying to power an arduino uno from the teensy at Vin and GND to teensy 5v and GND, but I'm not getting any power,


    when tried powering the arduino and leaving GND connected to teensy, the arduino is powered but no readings at the teensy, do I need to connect also RX from arduino to teensy TX for serial to work ?

    Any ideas or connection diagram possible.

    I'm using a voltage divider of 1.66K ,1K between the TX and RX on teensy

  2. #2
    bump! any help is appreciated!

  3. #3
    Senior Member
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    With both of them separated, can you program them from a PC individually? Do they work fine separately?

  4. #4
    Senior Member PaulStoffregen's Avatar
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    First, answers I can give...

    If you're sending data in only 1 direction, from Uno to Teensy, you only need 1 signal plus GND. If using Teensy 3.2 or 3.5, you can connect it directly to Teensy's RX1 pin (pin 0), because those boards are 5V tolerant. For Teensy LC, 3.6, 4.0, you must use resistors or a chip to reduce the signal to 3.3V.

    On the power, the best way to troubleshoot is with a voltmeter. Uno has 2 ways to receive power. We don't know if you're using USB or the DC power jack. Depending on how you've connected the wires, which also isn't clear (at least to me), which of Uno's inputs you use may or may not matter. A voltmeter can show you conclusively whether Uno is actually sending 5V power.

    Now, regarding answers I can't give...

    In the answers above, I already had to guess which Teensy you're using and which power input you're using on Uno. Lack of these sorts of details makes answering your question much harder. When you leave out key info, often the result is nobody replies. Even when you do get replies, the answers can't nearly as helpful as they could be, because we have to guess so much. You had to "bump" this thread. Please understand this almost certainly is due to your message having imprecise descriptions, no source code, and no photos.

    If you need more help with this, please do yourself a huge favor and take photos that clearly show your wiring. Usually a few pictures are needed, both close ups so we can see the connections, and wide angle shots so we can see where the wires go.

    Likewise, show us the exact code you're running on each board. Even if the code seems trivial and unnecessary, show it anyway. If you look over the many other threads on this forum, you'll see countless cases where we figured out why something wasn't working because of a subtle code problem. We can help you like that too, but only if you show the actual code from each board. That's why we have the "Forum Rule" at the top of every page... so we can help you better!

  5. #5
    yes, the serial works fine on arduino on it's own, but not sending to teensy 3.6, the lights don't light up when they are both connected (RX/TX Lights)

  6. #6
    Quote Originally Posted by pfzzz View Post
    yes, the serial works fine on arduino on it's own, but not sending to teensy 3.6, the lights don't light up when they are both connected (RX/TX Lights)
    Here is the code:
    https://github.com/0mars/arduino


    mux_duino: multiplexed pots
    teensy app: https://github.com/0mars/arduino/blo...MicroDexed.ino

  7. #7
    Senior Member PaulStoffregen's Avatar
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    I looked at this code briefly. It is a very large program and I have very little time today.

    Nowhere in MicroDexed.ino are Serial1, Serial2, Serial3, Serial4, Serial5 or Serial6 used. So I do not understand how this code could possibly attempt to communicate with an Arduino Uno using any of its 6 serial ports. Maybe the serial communication code is located in one of the other files? Sorry, I do not have time to read through a huge amount of code. I want to help you, but I have limited time.

    Also unclear is which of the 6 serial ports you are using. The only info I see is "using a voltage divider of 1.66K ,1K between the TX and RX on teensy". But which TX & RX pins? What is the actual circuitry? No diagram, no photo, no clear description.

    I also do not see the code used for Arduino Uno.

    Could you create 2 very small and simple programs which do the board-to-board communication? Yes, this is extra work for you. But as you have shown, with a huge program for Teensy and no program of the Arduino Uno, and no photos or diagrams of how the hardware is actually connected, it would take a miracle (and many hours of work) for anyone to help.

    Please, if you want help, show us how you connected these boards. Use photos. Then give us small but complete programs to run on BOTH boards. The code should be small and simple, showing only the communication problem. Anyone reading should be able to copy the code into 2 Arduino windows and upload to these 2 boards to recreate the problem.

    I want to help you get this working, and I have both of these boards here and plenty of wires and resistors to quickly recreate the connection between them. But I can't spend a lot of time reading through a huge pile of code and guessing the code on the other board, not to mention guessing which pins you actually used.

  8. #8
    Quote Originally Posted by PaulStoffregen View Post
    I looked at this code briefly. It is a very large program and I have very little time today.

    Nowhere in MicroDexed.ino are Serial1, Serial2, Serial3, Serial4, Serial5 or Serial6 used. So I do not understand how this code could possibly attempt to communicate with an Arduino Uno using any of its 6 serial ports. Maybe the serial communication code is located in one of the other files? Sorry, I do not have time to read through a huge amount of code. I want to help you, but I have limited time.

    Also unclear is which of the 6 serial ports you are using. The only info I see is "using a voltage divider of 1.66K ,1K between the TX and RX on teensy". But which TX & RX pins? What is the actual circuitry? No diagram, no photo, no clear description.

    I also do not see the code used for Arduino Uno.

    Could you create 2 very small and simple programs which do the board-to-board communication? Yes, this is extra work for you. But as you have shown, with a huge program for Teensy and no program of the Arduino Uno, and no photos or diagrams of how the hardware is actually connected, it would take a miracle (and many hours of work) for anyone to help.

    Please, if you want help, show us how you connected these boards. Use photos. Then give us small but complete programs to run on BOTH boards. The code should be small and simple, showing only the communication problem. Anyone reading should be able to copy the code into 2 Arduino windows and upload to these 2 boards to recreate the problem.

    I want to help you get this working, and I have both of these boards here and plenty of wires and resistors to quickly recreate the connection between them. But I can't spend a lot of time reading through a huge pile of code and guessing the code on the other board, not to mention guessing which pins you actually used.

    thank you so much for your reply, I will try to recreate the problem using a small teensy program and post back

  9. #9
    Senior Member+ KurtE's Avatar
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    I also took a quick look through here to see if there was anything Obvious.

    As Paul mentioned, in cases like this, it would be very helpful to see a picture showing the setup.

    The only thing I believe I understand is that you probably have a USB connector hooked up to a Teensy 3.6? And from this you have wires the connect the VIN and GND pins of the Teensy to the +5v and GND pins of Arduino Uno?

    And doing a quick search in Sublime Text of your project I only see Serial1 is ever used? I am guessing that assuming the voltage divider is wired correctly, it should convert the TX of UNO (pin 1) from 5v to T3.6 (pin 0) to 3.12 v which should work,
    But again still just guessing.

    Then there is the question of what programs are running on both processors. Are they both configured for the same Baud rate?

    What do you mean by no reading?

    Again can only guess.

  10. #10
    Quote Originally Posted by pfzzz View Post
    thank you so much for your reply, I will try to recreate the problem using a small teensy program and post back
    receiver teensy 3.6:
    https://github.com/0mars/arduino/tre...er/serial_recv

    sender uno:
    https://github.com/0mars/arduino/tree/master/mux_duino
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  11. #11
    anyone looking into it, thanks!!

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