ATmega32u4 DFU Bootloader Basic Question

Discussion in 'Embedded Systems and Microcontrollers' started by sycross, Jun 15, 2013.

  1. sycross

    Thread Starter New Member

    Jun 15, 2013
    Hello all,

    I am currently designing a PCB for a new musical interface that I'm working on. The interface is quite simple. I call it "The FaderKeyboard" since the entire thing will just consist of a row of 48 slide pots. I would like to make this into a finished product and then share it with others by putting it on Kickstarter this summer.

    I am new to micro-controllers and electronics in general, so please excuse me if this is a dumb question. I have searched online for an answer, but everything I found has gone over my head.

    For this project, all I need is a circuit which reads 48 analog inputs and spits out MIDI through USB. Since I'm new to circuit design, I thought I would work off of pre-existing schematics. Here was my initial plan:

    1. Duplicate the necessary parts of the Teensy 2.0 onto my PCB:
    (schematic from Paul Stogreffen's site)

    2. Hook up some multiplexers to the duplicated Teensy, as so:
    (this is again taken from Paul's site-- for my purposes I would not have any digital readings, just analog ones)

    This seems straight-forward enough to me, but I'm a bit confused about how I would program the ATmega32u4 if I were to order a PCB like this. The assembly house would be soldering fresh ATmegas with the default Atmel bootloader on it, and I have no idea how I would interface with it. Based on what I've read online, I would need to connect the ATmega to my computer through USB, and then pull the HWB pin down while holding the reset button? And this would allow me to program the MCU using Atmel's Flip software?

    I was hoping to get rid of the reset button from the Teensy schematic. Is there a way to program a fresh ATmega32u4 purely through USB, without needing to physically touch the board?

    Thanks in advance for any guidance.