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Thread: Connecting two PCBs together

  1. #1

    Connecting two PCBs together

    Hi,
    currently I am working on a project in which I will have multiple modules. And I want to make my own teensy 3.2 on separate PCB with usb and i2C connection for connecting to the difference modules. But I encountered a problem with interconnecting these two PCBs together.
    Could you please submit some ideas.

  2. #2
    Senior Member+ MichaelMeissner's Avatar
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    You probably need to go into more detail of exactly how you will interconnect things, with pictures showing the teensy and the other devices (and list what those devices are). In general, it is simplest if all of the boards run off of the 3.3v power from the Teensy, and if the wires are kept as small as possible. Have you tried interconnecting just one device at a time to see if the Teensy can talk to that device in isolation?

    In terms of i2c on the Teensy, do you have the standard 2 pull-up resistors installed? Generally, you will need one resistor between SDA (pin 18/A4) and 3.3v, and another between SCL (pin 19/A5) and 3.3v. A usual value for the Teensy is 2.2K or higher resistors. Teensy can usually work with 4.7K pull-up resistors some devices have installed to work with 5v i2c systems. If you have resistors that are more than 2.2K for pull-ups, you might not be able to use the higher i2c speeds. You only need one set of i2c pull-up resistors on the bus. If you have multiple devices, each with their set of pull-ups, you may need to disable one or more. Note, complex i2c buses can mean the default pull-up resistors need to be adjuste.

  3. #3
    Quote Originally Posted by MichaelMeissner View Post
    You probably need to go into more detail of exactly how you will interconnect things, with pictures showing the teensy and the other devices (and list what those devices are). In general, it is simplest if all of the boards run off of the 3.3v power from the Teensy, and if the wires are kept as small as possible. Have you tried interconnecting just one device at a time to see if the Teensy can talk to that device in isolation?
    I want to have a separate teensy with three usb connectors one for regular usb and onther twos for i2c to connect it to other modules, they wont be far a way from each other. And I want on the teensy some kind of connector with which i could interconnect the theensy with a 10 by 10 cm board on which would be some buttons, encoders, potentiometrs etc.


    Quote Originally Posted by MichaelMeissner View Post
    In terms of i2c on the Teensy, do you have the standard 2 pull-up resistors installed? Generally, you will need one resistor between SDA (pin 18/A4) and 3.3v, and another between SCL (pin 19/A5) and 3.3v. A usual value for the Teensy is 2.2K or higher resistors. Teensy can usually work with 4.7K pull-up resistors some devices have installed to work with 5v i2c systems. If you have resistors that are more than 2.2K for pull-ups, you might not be able to use the higher i2c speeds. You only need one set of i2c pull-up resistors on the bus. If you have multiple devices, each with their set of pull-ups, you may need to disable one or more. Note, complex i2c buses can mean the default pull-up resistors need to be adjuste.

    Yes I have the ressistors in place, but I will redo them on the separate teensy board

  4. #4
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    Be sure to have a common ground connection to all of your modules. This fellow seemed to have the same problem and common ground resolved it.


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