I designed and printed a PCB for my MIDI controller project with a modified Arduino Micro microcontroller essentially built into the design. I swapped out the USB Micro for a USB-C type port (just using the 2.0 protocol). Although I can program the board via ICSP, including getting it to run my Arduino sketches (which I have tested by having it light up the LEDs in a certain pattern, which works as expected), and the fact that it receives power via USB, the problem is that I cannot get the device to connect to my PC over USB - it is not recognized as a USB device, and cannot seem to send or receive data over USB. I'm not sure if I've done something wrong in the design or if I am simply missing something, but could use some advice, as in order to function as intended, the board will need to be able to communicate over USB.

I have tested with various USB-A to USB-C cables and USB-A to Micro cables (tested with other Arduinos) and a Micro to USB-C adapter.

As per various instructions I found online, I connected pull-down resistors of 5.1k Ohms to CC1 and CC2, left SBU1 and SBU2 unconnected as I was planning to use 2.0 protocols to keep things simple (as a related question, can these actually be used to make use of 3.0+ protocols in a design like this with an ATMEGA32U4? Would this be considered better practice in this case and potentially bypass the error?), and wired up D- and D+ as shown in the schematic below; with a EZJZ0V500AA Varistor between each and GND and running through a 4D03WGJ0220T5E Resistor network (which I don't know much about, including whether this type of component has any polarity? I simply tried to follow how the same sort of component was used in the official Arduino Micro schematics) and finally into pins 3 and 4 of the ATMEGA32U4.

This is the original schematic of the board as it was assembled, but as a result of some power issues with this same board which I have since sorted out with help in a separate post Why wont my custom Arduino-Micro-based board receive power via USB?, I had to bypass the 5V regulator and just use VUSB as +5V, so I will put the updated schematic reflecting these changes below the original (I wouldn't think it would affect this issue, but I'm not that experienced and want to err on the side of providing as many details as possible)

Original Schematic: Original Schematic

Revised Schematic: Revised Schematic


| Designator                                             | Value                   | Component                |
| C_ARD_1, C_ARD_2, C_ARD_6, C_ARD_9, C_ARD_10, C_ARD_11 | 100n                    | CL05B104KO5NNNC          |
| C_ARD_3, C_ARD_14                                      | 22u                     | RVT22UF16V67RV0017       |
| C_ARD_4, C_ARD_5, C_ARD_7                              | 1uF                     | CL05A105KA5NQNC          |
| C_ARD_12, C_ARD_13                                     | 22pF                    | 0402CG220J500NT          |
| D_ARD_2                                                | CD1206-S01575           | CDSU4148-HF              |
| F1                                                     | MF-MSMF050-2 500mA      | MF-MSMF050-2             |
| J3                                                     | USB_C_Receptacle_USB2.0 | KH-TYPE-C-16P            |
| L1                                                     | green                   | 19-217/GHC-YR1S2/3T      |
| L2                                                     | MH2029-300Y             | BLM21PG300SN1D           |
| ON1                                                    | blue                    | 19-217/BHC-ZL1M2RY/3T    |
| R_ARD_1, R_ARD_2, R_ARD_4, R_ARD_9                     | 10K                     | 0402WGF1002TCE           |
| R_ARD_5, R_ARD_6, R_ARD_7, R_ARD_8                     | 1K                      | 0402WGF1001TCE           |
| R_ARD_10, R_ARD_11                                     | 5.1k                    | 0402WGF5101TCE           |
| RP3                                                    | 22R                     | 4D03WGJ0220T5E           |
| RX1, TX1                                               | yellow                  | 19-213/Y2C-CQ2R2L/3T(CY) |
| T1                                                     | FDN340P/PMV48XP         | PMV48XP                  |
| T2                                                     | PMV48XP                 | PMV48XP                  |
| U1                                                     | ATMEGA32U4-XUMU         | ATMEGA32U4-MU            |
| U2                                                     | NCP1117-5               | NCP1117ST50T3G           |
| U4                                                     | LP2985-33DBVR           | LP2985-33DBVR            |
| Y3                                                     | 16MHz KX-7              | 3225-16.00-10-10-10/A    |
| Z1, Z2                                                 | CG0603MLC-05E           | EZJZ0V500AA              |
  • 1
    Did you try to burn the bootloader over ICSP?
    – chrisl
    Sep 27, 2022 at 22:26
  • "as a side question" it's probably better than you don't ask that in the same question. I gather you sorted out your power problem and this is now about about data. Or at least I hope that's what's going on. If so, you may want to make that really clear before people start trying to close it as a duplicate. Like before, if you mention that you're testing with a USB-A to USB-C cable, this eliminates any concerns regarding the design or implementation or design surrounding CC1/CC2. They become a non-issue, because they're handled by the cable in that case.
    – timemage
    Sep 27, 2022 at 22:26
  • @chrisl Yes, I have successfully burned the bootloader over ICSP prior to testing it over USB
    – Stuart
    Sep 27, 2022 at 23:11
  • @timemage Appreciate the advice, I am fairly new to this platform so wasn't completely sure the best way to go about asking multiple related questions, etc. I did indeed solve the power issues and thought it might confuse things to mention that again here since this seems to be a mostly unrelated issue, but I'll make a note of it in an edit.
    – Stuart
    Sep 27, 2022 at 23:25
  • Did you do something like select Arduino Micro and burn the bootloader through ISP? Or did you install use the DFU loader?
    – timemage
    Sep 27, 2022 at 23:54

1 Answer 1


Well I finally found the source of the problem, many thanks to everyone here who helped me narrow things down and kept pointing me in the right direction. After figuring out that D+ and D- were getting pulled appropriately by the chip I decided to desolder the USB port on the board, cut a USB-A 2.0 cable and solder the leads directly to the board and, suddenly, it worked. After this I realized the problem must have been with the USB port on the board and upon comparing the datasheet to my pcb file, I realized that the footprint I used and the one in the datasheet had the pins laid out in a different order.

I feel a bit embarrassed for taking up people's time on such a stupid error I made (and admittedly didn't even provide enough information for anyone to be able to figure out for me, despite all of your patience and helpful advice), but at the same time I am both relieved I figured out the problem and grateful for all the help I got on this post, I'm not sure how long it would have taken me to figure out without your suggestions. I learned a lot about the layout of arduino boards, the purposes of various components in said boards, the importance of double checking footprints, and about better practices for asking for assistance.

As a note on "post etiquette" or whatever you would call it, since everyone provided assistance in comments, I didn't see a way to close the post without answering my own question (I am new to posting here), so I hope that is an acceptable way to do so.

  • It is perfectly fine to answer your own question and mark it as accepted. You might want to read some pages of the help center to learn more. Oct 2, 2022 at 9:15

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