Home Forum Request for help Atmel Processor Wiring (Custom Arduino Board)

This topic contains 3 replies, has 1 voice, and was last updated by  Kieran Mesquita 3 years, 10 months ago.

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  • #2317

    I’m trying to create a custom Arduino board based off the Arduino Leonardo (with inbuilt radio, RJ9 jacks for peripherals and batteries). The schematics here: https://www.arduino.cc/en/uploads/Main/arduino-leonardo-schematic_3b.pdf are a little confusing to me. Is anyone able to give me a hand with this?

    #2318

    Andrew-MOAMind
    Participant

    I would recommend something based off the Duemilanove if it meets your requirements. The ATMega328P is a lot easier to work with I find and I have built a few PCBs with them myself so I am a little more familiar with them.

    The top right corner of that schematic is completely useless, it is additional documentation on what outputs are associated with which pins, just in a clearer way than is demonstrated on the top left. The main things you need are the USB connections, Crystal with load capacitors, pull up resistor on the reset line & the ICSP header. A lot of the other ‘stuff’ is optional. Although I would keep the 22 ohm resistors inline with the D+ and D- usb signals.

    In an ideal world the USB traces should be impedance matched as they can be high speed signals. Doing this in eagle (which i assume you are using) is a bit of a pain and not really required for a micro like this one, provided you keep the traces short.

    If you have more specific questions I can be a bit more useful.

    #2319

    Andrew-MOAMind
    Participant

    Oh You may be interested in this as well…
    [media=youtube]Bdm_iSLiBds[/media]

    #2320

    I’m using the Leonardo as size/battery is a constraint here.
    http://murchlabs.com/wp-content/uploads/2013/06/fritzing-atmega32u4-usb.png
    this cleared things up.

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