I've been using cloned Arduinos for years now. And never had any problems with them, until this week.

I ordered three cloned Arduino nano's to build an UPDI programmer. Installed a new CH340 driver (because new fresh OS install) Connected the board and on upload in the Ardiuino IDE I got this message:


avrdude: ser_open(): can't set com-state for  “\\.\COM13”

First checked the device manager, which seemed fine:


  • Checked the other two boards
  • Used another computer
  • Used 3 other cables
  • Reset the device
  • Tried all the tricks I could find online

Nothing worked. I even re-burned the bootloader using a ICSP programmer, which worked (so the Mcu must be working right?):

But still, via USB the board would not work.

Then I found this fairly recent reddit post mentioning counterfeit CH340 chips: https://www.reddit.com/r/arduino/comments/13926kl/im_having_the_uploading_error_erroravrdude_ser/
Apparently the company that produces these chips has pulled a FTDI gate sort of action and disabled the counterfeit chips in their drivers.

The counterfeit IC's can be recognized by not having any markings on them.. so I checked mine and:

Indeed, no markings on the serial chip (the one above) no… it's not the lighting, there are no markings on there. Below is a working one with markings.

You might get boards working with an older CH340 driver which still works, I haven't tried this because this is not very future proof. Also the boards can still be used with ICSP if you don't need the USB function. Because I want to make an UPDI programmer I ordered new boards, those had markings and worked without any problem.