I'm working on an embedded linux machine and trying to read a USB devices input stream, but for some reason I don't have any such thing in my /dev directory. I would assume it would be something like /dev/ttyUSB01 or /dev/input/usb or something similar, but it's not there. dmesg returns the following
[ 195.863911] input: GIT GIT USB READER as /class/input/input2
[ 195.864259] generic-usb 0003:1234:5678.0001: input: USB HID v1.00 Keyboard [GIT GIT USB READER] on usb-0000:00:0f.4-1/input0
I've scanned through /sys/class/input/input2 and I am not really sure what I'm looking for. Maybe someone could point me in the right direction?
Had the same problem a few days ago and we discovered this workaround.
You could do the following command at the terminal:
cat /proc/bus/input/devices
This will list your devices connected, and your devices should be on the list. For instance, one item on there appears this way for me:
I: Bus=0011 Vendor=0002 Product=000a Version=0000
N: Name="TPPS/2 IBM TrackPoint"
P: Phys=synaptics-pt/serio0/input0
S: Sysfs=/devices/platform/i8042/serio4/serio5/input/input15
U: Uniq=
H: Handlers=mouse1 event15
B: PROP=0
B: EV=7
B: KEY=70000 0 0 0 0
B: REL=3
Under Handlers, you'll notice that event15 shows up. You can access the data stream by referencing /dev/input/event15 in my case. You'll have to figure out what it is in your case
Check out /dev/input/by-path and look for your usb-0000:00:0f.4-1. On my Ubuntu box that's a symbolic link to the device.
Have you tried using mdev? It's a lightweight alternative to udev and it populates /dev. If hotplugging is not enabled you might need to run it manually.
To scan /sys and create devices, try:
mdev -s
Related
I have a couple of Maginon SP-1E smart plugs which can be triggered remotely. I manage them through HA, but did not find a way yet to just read out the state of the switch. There is a command to switch on or off and a result is returned. The plug is running Busybox (v1.12.1 (2014-07-31 06:32:52 CEST) multi-call binary) and is somewhat stripped down, but telnet, ifconfig, nvram_get, nvram_daemon, nvram_set, flash, gpio are all binaries that are available for use.
To turn on:
http://192.168.0.52/goform/SystemCommand?command=GpioForCrond+1
Returns:
gpio_set_dir: gpio=2, dir=0
gpio_set_dir: gpio=1, dir=1
InitGpio() success, fd = 3
Get GPIO1 = [01]
To turn off:
http://192.168.0.52/goform/SystemCommand?command=GpioForCrond+0
Returns:
gpio_set_dir: gpio=2, dir=0
gpio_set_dir: gpio=1, dir=1
InitGpio() success, fd = 3
Get GPIO1 = [00]
So clearly there seems to be a way to toggle (and read) the switch state, but I cannot find a way to do so. Any hints? The source code for the plug is available here.
I have an USBhub (D-Link DUB-H7) connected to my laptop with Windows 10. Connected to the hub are 4 identical PEAK dongles to talk to a CANbus. Now, my problem is to programmatically identify these 4 seperate dongles and knowing which one is which. The dongles are fixed in the hub.
To start I downloaded and installed USBDeview to view my devices. In the program I can see my 4 PCAN-USB dongles and I can see that their Instance ID are different. That's good, now I have my identifier. However, once I try to get the ID's with Python things aren't looking good. This is my following test program:
import win32com.client
wmi = win32com.client.GetObject("winmgmts:")
input("Connect the hub")
dongle_list = [(usb.name, usb.DeviceID) for usb in wmi.InstancesOf("Win32_USBHub")]
input("Disconnect the hub")
nod_list = [(usb.name, usb.DeviceID) for usb in wmi.InstancesOf("Win32_USBHub")]
diff = list(set(dongle_list) - set(nod_list))
for d in diff:
print(d)
Running this gives me only 2 new usb devices and the ID's point to the USBhub rather than the dongles connected to the hub. I also tried with wmi.InstancesOf("CIM_USBDevice") but the result stays the same.
('Generic USB Hub', 'USB\\VID_05E3&PID_0608\\5&4A43CD6&0&4')
('Generic USB Hub', 'USB\\VID_05E3&PID_0608\\6&9EBFB9C&0&4')
So how can I retrieve the usb information of the devices connected to the USBhub using Python or powershell/cmd invoked by Python?
Another route I was thinking I could take is by using port identifiers. If I disconnect a dongle I can see that it was connected to Port_#0001.Hub_#000x, where is x is a positive integer. So maybe I could poll the port to see if the dongle is connected and then I too know which one is which (dongles are fixed in the hub). Although I think that using the Instance ID is more foolproof.
I ended up creating a powershell command and invoke that using Python. I noticed however that the InstanceID's are hardware addresses of the the USBhub and not the dongles.
I also noticed that the dongles sometimes switch their addresses related on how they were connected. So I also needed to disable them and enable them again in the order I want.
This is what I have now:
poll_cmd = """
$ret = (Get-PnpDevice | ? {($_.description -like "*pcan*") -and ($_.status -eq "ok")} | sort instanceid).instanceid;
$ret | % {Disable-PnpDevice $_ -Confirm:$False};
$ret | % {Start-Sleep -Seconds 1; Enable-PnpDevice $_ -Confirm:$False};
$ret
"""
usbs = (
subprocess.check_output(["powershell.exe", poll_cmd])
.decode()
.strip()
.split("\r\n")
)
usbs holds the list of usb dongles I'm interested in.
However this gave me one more problem: UAC. I need admin rights to enable the usbs. And used the top answer from Request UAC elevation from within a Python script? to give my program admin rights.
We have a Linux device which has a speaker and MIC devices. These devices are shared among different modules - example a VOIP call can use speaker, a hazard Warning system can use speaker, a Voice prompt can use a speaker etc:
There seems to be a function in ALSA which uses pcm to provide the status.
int snd_pcm_status (snd_pcm_t * pcm, snd_pcm_status_t * status)
However the *pcm is returned by snd_pcm_open. We do not want to open the device as we would like to know the status of the device using its "name"
Alsa API is here
How can we check if a resource/device is busy without opening it and using its name?
The same information for playback stream X of device Y on card Z is available in the file /proc/asound/cardZ/pcmYp/subX/status; when the device is not open, it just says "closed".
Please note that you cannot use this information to decide if you can open the device, because some other process could have openend it just after you've read this information. The only way to check if you can open it is to actually try.
Though it requires /dev/dsp, this seems to work:
#!/bin/dash
## If the speaker is not used by any, returns 0, and prints "free"
## Otherwise, returns 1 and prints "not free"
iExit (){
trap '' 0
exit $1
}
iCatch (){
# The speaker is already in use
echo not free
iExit 1
}
trap iCatch 0
{
exec 3>&1 1>/dev/dsp
# If the execution reaches here, the speaker is not used by any
# Otherwise, it's catched by iCatch
exec 1>&3
echo free
iExit 0
} 2>/dev/null
Without PulseAudio, it seems on some PC only one output is accepted at one time; on others simultaneous playbacks are allowed. But even in the latter case, the above code works.
NB: The above code does not work with bash; for bash, simply use if/else rather than trap.
NB 2: /dev/dsp may be lacking depending on the kernel configuration.
The dev suggested to ask here to get more help.
This is what is happening, I bought a Raspberry Pi (second one, I know how to handle them, and I'm used to apt and ssh) and a Trendnet TFM561U modem, downloaded NOOBS, did the initial setup with an extra in the shape of Webmin. So far aside from Webmin, it's a vanilla Raspbian. I then downloaded JCblock ( http://sourceforge.net/projects/jcblock/ ) and following the instructions here http://weeklytechforum.com/2013/03/28/block-unwanted-calls-with-a-raspberry-pi/ I edited the files that needed editing and finally compiled. I found out what serial port the modem was using (same as the guide! cool) and finally proceeded to test it. That's where the trouble started.
The differences between me and the guide is that I'm in Italy, so the dev of JCblock made me edit the source with a few extra lines of code to talk to the modem... now it's a great time to point out that while I can edit code and recompile it, this is C and I absolutly have no clue about it, knowing just some basics from Pascal and a bit of Visual Basic, so in the end I'm editing the source blindly, just guessing where things need to go. Anyway the edits are to send the Country Code command: AT+GCI=59\r and Caller ID command: AT+VCID=1\r but we do not seem to be geting caller ID data from the modem.
What I'm expecting to see: I call with my cellphone (and that number is in the blacklist) the Raspberry doesn't make the phone ring, or in case of wrong configuration of the blacklist I get some output that will show a call not filtered.
What I get: the phone rings, the modem data light flashes, the program dosen't output anything.
Any help will be appreciated, thanks.
EDIT:
So, I went ahead and used NCID to see what would happen.
As it generates a cornucopia of data, I think it can be useful
Started: 10/27/2014 22:24:54
Server: ncidd (NCID) 1.0
API: 1.0 Feature Set 1 2 3 4
Command line: ncidd
-Dv3
Logfile: /var/log/ncidd.log
Processed config file: /etc/ncid/ncidd.conf
Verbose level: 3
Configured to send 'cidlog' to clients.
Configured to send 'cidinfo' to clients.
Helper tools:
/usr/bin/cidupdate
/usr/bin/ncidutil
Processed alias file: /etc/ncid/ncidd.alias
Alias Table:
Number of Entries: 1
Leading 1 from a call required in an alias definition
Calls in the blacklist file will be terminated
Processed blacklist file: /etc/ncid/ncidd.blacklist
Blacklist Table:
Number of Entries: 12
Calls in the whitelist file will not be terminated
Processed whitelist file: /etc/ncid/ncidd.whitelist
Whitelist Table:
Number of Entries: 0
CID logfile: /var/log/cidcall.log
CID logfile maximum size: 110000 bytes
Data logfile not present: /var/log/ciddata.log
Maximum number of clients/gateways: 25
Telephone Line Identifier: -
TTY port opened: /dev/ttyACM0
TTY port speed: 19200
TTY lock file: /var/lock/LCK..ttyACM0
TTY port control signals enabled
CallerID from AT Modem and optional gateways
Handles modem calls without Caller ID
Sent Modem 20 of 20 characters:
AT Z S0=0 E1 V1 Q0
Modem response: 26 characters in 1 read:
AT Z S0=0 E1 V1 Q0
OK
Try 1 to init modem: return = 0.
Modem initialized.
Sent Modem 6 of 6 characters:
ATI3
Modem response: 39 characters in 1 read:
ATI3
CX93001-EIS_V0.2002-V92
OK
Sent Modem 9 of 9 characters:
AT+GCI?
Modem response: 27 characters in 1 read:
AT+GCI?
+GCI: 59
OK
Sent Modem 13 of 13 characters:
AT+FCLASS=?
Modem response: 32 characters in 1 read:
AT+FCLASS=?
0,1,1.0,8
OK
Sent Modem 11 of 11 characters:
AT+VCID=1
Modem response: 17 characters in 1 read:
AT+VCID=1
OK
Modem set for CallerID.
Hangup option set to hangup on a blacklisted call
Modem used for CID and to terminate calls
Network Port: 3333
Debug Mode
Not using PID file, there was no '-P' option.
Modem is fd 4
NCID connection socket is sd 5 pos 1
RING
CIDINFO: *LINE*POTS*RING*1*TIME*22:25:21*
CIDINFO: *LINE*POTS*RING*0*TIME*22:25:33*
What I can tell from this, is that it should be properly set up to hang up for a blacklisted number (my cellphone, for testing purposes) and that no caller id gets to the software. About that, it's important to point out how we have a mess of different phones (make, model, cordless, wired...) at home, and all of them do show 1 missed call from me. So at least I can confirm that the caller id is being sent.
I looked on Trendnet TFM561U description page and Amazon for this modem and didn't see "caller ID" in the description.
Your modem looks like it has Caller ID because its response to the activate caller ID command is "OK":
AT+VCID=1
OK
But looking at
Testing Modem Caller ID Support with HyperTerminal (or Putty) page
However, if, in step 8), the modem responded with "OK", then you probably have the correct string. In this case, either your phone line does not have caller id enabled (this can be tested with a hardware caller id device), or the modem does not support caller id. The latter is possible even if, in step 8), the modem responded with "OK", since many modems use the same firmware regardless of whether the modem contains the appropriate caller id hardware. In other words, many modems don't know whether they have caller id support!
I would say return your modem and get one that has "caller ID" in the description.
I attach 2 webcam to computer and it was listed in /dev folder: /dev/video0; /dev/video1.
Can you help me write C code to get serial number of webcam with input: /dev/video[0;1]
Just ran into this same problem and it took a bit to find the solution. Any solution which starts with "just use lsusb" is incorrect. You can figure out the devices serial, but none of the extra information it provides help you determine which /dev/video it links to.
Solution:
/bin/udevadm info --name=/dev/video1 | grep SERIAL_SHORT
Output:
E: ID_SERIAL_SHORT=256DEC57
Based on the hint of using udevadm and the tutorial from http://www.signal11.us/oss/udev/ I got below code to get the serial info of my webcam.
#include "stdio.h"
#include <libudev.h>
int main(int argc, char **argv)
{
struct udev *udev;
struct udev_device *dev;
struct udev_enumerate *enumerate;
struct udev_list_entry *list, *node;
const char *path;
udev = udev_new();
if (!udev) {
printf("can not create udev");
return 0;
}
enumerate = udev_enumerate_new(udev);
udev_enumerate_add_match_subsystem(enumerate, "video4linux");
udev_enumerate_scan_devices(enumerate);
list = udev_enumerate_get_list_entry(enumerate);
udev_list_entry_foreach(node, list) {
path = udev_list_entry_get_name(node);
dev = udev_device_new_from_syspath(udev, path);
printf("Printing serial for %s\n", path);
printf("ID_SERIAL=%s\n",
udev_device_get_property_value(dev, "ID_SERIAL"));
printf("ID_SERIAL_SHORT=%s\n",
udev_device_get_property_value(dev, "ID_SERIAL_SHORT"));
udev_device_unref(dev);
}
return 0;
}
You can use lsusb, but you need to add verbose flag and make sure you use sudo with it, otherwise the serial will be incorrect.
sudo lsusb -v
If that is too verbose, then run lsusb to get the device id:
$ lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 012: ID 1ab1:0e11 Rigol Technologies
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Then run lsusb with device flag and grep the serial number.
So for the serial number of Rigol device:
$ sudo lsusb -s 012 -v|grep -i iserial
iSerial 3 DP8C221100000
Playing around with libusb, it looks like there's a standard getSerialNumber() method. Unfortunately, not all USB devices implement this. I have a couple cheap $4 webcams that return None for it. These interfaces expose other metadata, like VendorID and ProductID, which I've seen some code try and use as a unique identifier, but it's not guaranteed to be unique, especially if you have multiple devices of the same make and model.
But assuming you get a serial number for your device, the next problem is figuring out which /dev/videoN file it corresponds to. I have an old version of libusb installed, so I couldn't get the method working that returned the full sysfs path of the USB device, so instead I scrapped the output from hwinfo. I extracted all the chunks corresponding to cameras, and then from those I extracted the piece that looked like:
SysFS BusID: 1-1.2:1.0
USB devices actually form a complicated tree, and that BusID encodes where the device is located in that tree.
You can then take that BusID to find where the device lives in the filesystem as well as the video path, which should be at:
/sys/bus/usb/devices/<BusID>/video4linux/
That's a directory, and inside it you'll find a videoN file matching one in /dev.
Looking at lsusb you find out that it uses libusb, it has many functions, notably for usb device handling and enumeration. libudev might be relevant too.
Alternatively, popen the lsusb command...