Just a quick check of microcontroller schematic before getting the PCB printed

[j4cobgarby]

Here's a schematic for a keyboard I'm designed (the actual keyboard keys aren't included in this screenshot, of course).

Does this schematic look reasonable? I've read that I can program the Atmega32u4 over the USB connection using the pre-programmed DFU bootloader, but just in case that doesn't work I've got 6 pins coming off the chip which I can use for the 6-pin ISP interface.

I'd be very grateful if someone who's familiar with this microcontroller can look the schematic over quickly and give me any advice.

Thanks!

 

[Harald Kapp]

Looks like the GND connection to the USB port is missing (or maybe the label GND is taken as a connection, but I prefer placing a dedicated GND symbol):


Also: Vbus should only be connected to Vcc if the keyboard is powered from the USB interface.

It is also good practice to add decoupling capacitor right next to the controller's Vcc pins (2, 14, 24). Use 100 nF ceramic type and make the connections to the µC as short as possible:
one C between 1/2
one C between 14/15
one C from 24 to GND make the trace as short as possible, a GND plane would be best.

 

[Bluejets]

If you are just starting with the micro why not go for the Aduino Nano.
A little over $4.00 delivered complete with a usb lead.
Plenty to learn before one jumps in the "deep end" so-to-speak.

https://www.ebay.com.au/itm/Nano-V3...hash=item3d87907be0:m:mTI9Nncja344hajWWfn9oEg