I have a USB to serial adapter based on the SiLabs CP2101 chipset. I'm trying to use it with Debian 5.0 Lenny (armel architecture).
I seem to be able to get the proper kernel module to recognize the adapter, but it won't create /dev/ttyUSB0
.
I ran modprobe usbserial
and modprobe cp2101
and then connected the device, resulting in the following output from dmesg
:
usb 2-1: new full speed USB device using mv5182_ehci and address 8
usb 2-1: configuration #1 chosen from 1 choice
cp2101 2-1:1.0: cp2101 converter detected
usb 2-1: reset full speed USB device using mv5182_ehci and address 8
usb 2-1: cp2101 converter now attached to ttyUSB0
However, /dev/ttyUSB0
does not exist. There are no new files in /dev
.
find / -type f -name ttyUSB0
gives no results.
I did find a bunch of directories named ttyUSB0
that showed up after plugging in the device:
/sys/class/tty/ttyUSB0
/sys/bus/usb-serial/drivers/cp2101/ttyUSB0
/sys/bus/usb-serial/devices/ttyUSB0
/sys/devices/platform/mv5182_ehci.1/usb2/2-1/2-1:1.0/ttyUSB0
...
I found a file at /sys/bus/usb-serial/devices/ttyUSB0/ttyUSB0/dev
but it does not appear to be a serial port; I can't open it with screen
or Python's serial module.
To compare, I tried my Debian 6.0 development machine (which has a newer version of the cp2101 module now called cp210x
) and after seeing the "converter now attached to ttyUSB0" line in dmesg
, /dev/ttyUSB0
appears.
How do I get the cp2101
module to create /dev/ttyUSB0
? If I can't, what file do I open to access the serial port?
Best Answer
You could try making the device node manually. On my system
/dev/ttyUSB0
ismajor 188
andminor 0
. And hopefully, my supposition is correct that it's a typec
meaning character device (maybe tryu
for unbuffered character device ifc
doesn't work).If this worked, and the device file was appearing automatically before, something in your
udev
is messed up. There could also be an issue with USB subsystem settings or drivers.