My first atmega32u4 schematic

Hi, I am wanting to build my own PCBs using atmega32u4 and I dont know how to formulate every question I have regarding my schematic so you will see the relevant parts. Does it look okay?, notable omissions from the sparkfun design is the 3v3 regulator, and some stuff around that, and I am thinking if I ever order more than the initial batch, the green and yellow LEDs and the current limiting resistors wont be populated.

I just need an "adult" to look at my drawing :stuck_out_tongue:

  1. Need more 0.1uF caps, one for each AVCC and VCC pin.
  2. Probably need 22 ohm resistors on series from USB connector to D+, D-. Check the datasheet.
  3. Add a diode from Reset (anode) to 5V (cathode) to keep any spikes on reset from tricking the part into thinking a High Voltage mode is starting and then acting hung.

You may find 330 ohm will make the LEDs seem really bright. Try a test before soldering everything in place.

Hello @CrossRoads thank you very much for the review, Do I need a 0.1uF on VBus as well? Or does it hurt to have it there? Guessing its okay since 100nF is so small capacitance. Additional caps after the first one of that size is practically free.

Yes I totally forgot about the resistors on the usb data lines, I had them in there on my USB-C version of the schematic, thank you very much for reminding me!

Also should pin 2 and 4 of the clock be floating? It looks to me like that is how its done on the sparkfun brd file, but the symbol on the sch file has only two legs

On the crystal, read it's data sheet. Some have the pins connected to the case and recommend they be connected to Gnd for additional noise protection.
If you look at the datasheet for this one for example, it ways GND right on the pads.

On the caps, the 0.1uF are to be connected in parallel with 5V to the pins, not in series. From the pins to Gnd, with 5V connected to the pins.

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