i have designed a custom arduino board with the arduino nano schematic. I followed the schematic carefully and everything is okay.But if i connect the board to my pc, i keep seeing this error "unknown usb device (device descriptor request failed)". I have attached the picture of the error message. if i program the board using ICSP using another arduino as a programmer, the board will work well. So i guess it may have to do with usb serial bridge. i used FT232R in my design. I have tried many solutions on the internet but non is working for me yet. I will appreciate if anyone has solved this problem before to help me out. Thank you.
You're right that the issue is likely to be related to the USB-Serial bridge, but without seeing your schematic and board design no one is going to be able to offer any meaningful insight.
BJHenry:
You're right that the issue is likely to be related to the USB-Serial bridge, but without seeing your schematic and board design no one is going to be able to offer any meaningful insight.
Attached is the schematic and the PCB layout of the USB-Serial bridge section of the circuit. Sorry the pcb layout is a bit messy.
For USB data lines, layout really matters. If you have a look at the official Nano PCB files you'll see that the USB data lines are as short as possible and of similar length. The traces on your PCB aren't so direct, and even include two superfluous layer changes on one trace while the other has no layer changes.
You might need to redo that board if you want the onboard USB to work.
For USB data lines, layout really matters. If you have a look at the official Nano PCB files you'll see that the USB data lines are as short as possible and of similar length. The traces on your PCB aren't so direct, and even include two superfluous layer changes on one trace while the other has no layer changes.
You might need to redo that board if you want the onboard USB to work.
Thanks for your suggestion. I will consider that in my next design.
Could there any other possible reason, maybe from experience?
