I am trying to use an FTDI breakout board to connect to my custom made Arduino compatible board. I am using a new 16 inch macbook pro with USB-c ports, so I am using a dongle, in case that could be the problem.
Every time I try and upload a sketch I get the error: "can't open device "/dev/cu.usbserial-D306P6WW": Resource busy". When I check the /dev/ folder, both "/dev/cu.usbserial-D306P6WW" and "/dev/tty.usbserial-D306P6WW" show up, however in Arduino IDE I can only choose the "/dev/cu.usbserial-D306P6WW" option. I have installed FTDI VCP drivers, CH340 drivers and all kinds of other drivers to try and fix this issue. I have restarted countless times, and I have used a multitude of commands to check for programs hogging the usb port, but there is never a program. Plugging a harddrive into the same port causes no problems, so the port can't really be the problem. I am using a "FTDI FT231XS" board from Sparkfun.