user39838: I just built my own version of an Arduino Micro, using the ATMEGA32u4 chip. I burned the bootloader to it via another Arduino (Arduino Nano from banggood.com).
The Arduino Nano uses an ATMEGA328 chip, so it should work as an ISP programmer. None the less, I hooked up the Nano to my custom board, according to Sparkfun's Guide, and proceeded to burn the bootloader. The Arduino IDE says that I have successfully burned the bootloader.
However, when I plug in the newly burned custom board, Windows 10 throws the error, saying, USB Device Not Recognized followed by The last USB device you connected to this computer malfunctioned and Windows does not recognize it.
I have searched for a solution, but none seem to come up. My question is, what do I need to do in order to get this custom board working as an Arduino? Thanks!

user10794: You need a number of things to be true before the (new) bootloader will work:

The hardware needs to be wired correctly
You have used an appropriate crystal as the clock
You have installed the correct bootloader (ie. one for the Atmega32U4)
The fuses are set to boot into the bootloader
The fuses are set for the correct bootloader size
The fuses are set correctly for the clock type and the clock speed (for example, don't have the "divide clock by 8" bit set)

I have a sketch that analyses your chip signature and fuses which will also report on what bootloader it detected (assuming it is one from a recognized list). You could run that and amend your question to post the resulting display from the serial monitor.
I also have a sketch that programs a bootloader for various chips including the Atmega32U4. This sketch also sets the appropriate fuses.

39838: <p>I just built my own version of an Arduino Micro, using the ATMEGA32u4 chip. I burned the bootloader to it via another Arduino (Arduino Nano from <a href="https://www.banggood.com/" rel="nofollow noreferrer">banggood.com</a>).</p>

<p>The Arduino Nano uses an ATMEGA328 chip, so it <em>should</em> work as an ISP programmer. None the less, I hooked up the Nano to my custom board, according to <a href="https://learn.sparkfun.com/tutorials/installing-an-arduino-bootloader" rel="nofollow noreferrer">Sparkfun's Guide</a>, and proceeded to burn the bootloader. The Arduino IDE says that I have successfully burned the bootloader.</p>

<p>However, when I plug in the newly burned custom board, Windows 10 throws the error, saying, <code>USB Device Not Recognized</code> followed by <code>The last USB device you connected to this computer malfunctioned and Windows does not recognize it</code>.</p>

<p>I have searched for a solution, but none seem to come up. My question is, what do I need to do in order to get this custom board working as an Arduino? Thanks!</p>
 10794: <p>You need a number of things to be true before the (new) bootloader will work:</p>

<ul>
<li>The hardware needs to be wired correctly</li>
<li>You have used an appropriate crystal as the clock</li>
<li>You have installed the correct bootloader (ie. one for the Atmega32U4)</li>
<li>The fuses are set to boot into the bootloader</li>
<li>The fuses are set for the correct bootloader size</li>
<li>The fuses are set correctly for the clock type and the clock speed (for example, don't have the "divide clock by 8" bit set)</li>
</ul>

<p>I have a <a href="http://www.gammon.com.au/forum/?id=11633" rel="nofollow noreferrer">sketch that analyses your chip signature and fuses</a> which will also report on what bootloader it detected (assuming it is one from a recognized list). You could run that and amend your question to post the resulting display from the serial monitor.</p>

<p>I also have a <a href="http://www.gammon.com.au/bootloader" rel="nofollow noreferrer">sketch that programs a bootloader</a> for various chips including the Atmega32U4. This sketch also sets the appropriate fuses.</p>
