No Programming via Native USB port possible on Linux

Hi,

thanks for your extensive help!

If I type stty -F /dev/ttyACM0 1200
then udevadm outputs:

KERNEL[20012.111931] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.0/tty/ttyACM0 (tty)
KERNEL[20012.112021] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.0 (usb)
KERNEL[20012.112118] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.1 (usb)
UDEV  [20012.112896] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.1 (usb)
UDEV  [20012.113020] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.0/tty/ttyACM0 (tty)
UDEV  [20012.113649] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.0 (usb)
KERNEL[20012.124307] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/input/input34/mouse2 (input)
UDEV  [20012.125135] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/input/input34/mouse2 (input)
KERNEL[20012.128342] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/input/input34/event14 (input)
UDEV  [20012.129118] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/input/input34/event14 (input)
KERNEL[20012.132240] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/input/input34 (input)
KERNEL[20012.132356] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/0003:2341:003E.0017/hidraw/hidraw2 (hidraw)
KERNEL[20012.132414] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/0003:2341:003E.0017 (hid)
KERNEL[20012.132446] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2 (usb)
KERNEL[20012.132943] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4 (usb)
UDEV  [20012.133242] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/input/input34 (input)
UDEV  [20012.133295] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/0003:2341:003E.0017/hidraw/hidraw2 (hidraw)
UDEV  [20012.133866] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2/0003:2341:003E.0017 (hid)
UDEV  [20012.134354] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.2 (usb)
UDEV  [20012.135009] remove   /devices/pci0000:00/0000:00:14.0/usb3/3-4 (usb)
KERNEL[20012.485016] add      /devices/pci0000:00/0000:00:14.0/usb3/3-4 (usb)
KERNEL[20012.485430] add      /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.0 (usb)
KERNEL[20012.485738] add      /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.0/tty/ttyACM0 (tty)
KERNEL[20012.485779] add      /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.1 (usb)
UDEV  [20012.488233] add      /devices/pci0000:00/0000:00:14.0/usb3/3-4 (usb)
UDEV  [20012.489582] add      /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.1 (usb)
UDEV  [20012.489651] add      /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.0 (usb)
UDEV  [20012.493646] add      /devices/pci0000:00/0000:00:14.0/usb3/3-4/3-4:1.0/tty/ttyACM0 (tty)

So this looks good, but If I try to open the port I get the following:

$ picocom -b 9600  -p n -d 8 /dev/ttyACM0
picocom v1.7

port is        : /dev/ttyACM0
flowcontrol    : none
baudrate is    : 9600
parity is      : none
databits are   : 8
escape is      : C-a
local echo is  : no
noinit is      : no
noreset is     : no
nolock is      : no
send_cmd is    : sz -vv
receive_cmd is : rz -vv
imap is        : 
omap is        : 
emap is        : crcrlf,delbs,


FATAL: cannot open /dev/ttyACM0: Device or resource busy

One time it worked, but mostly not. I do not know why he thinks the resource is busy?