How to control LEDs from USB Webcam?

aurium · 12-29-2012, 09:55 AM

I have a new chinese webcam plugable by USB, with 6 LEDs to help night talks. However the lights do not turn on. Never! The cam has no buttons and the box says that is compatible with Linux.

I try the cam with Cheese and GUVCViewer. The cam works with no changes on LEDs and the mic do not works. (forgot the mic by now...)

Code:

$ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
...
Bus 001 Device 009: ID 0c45:62c0 Microdia Sonix USB 2.0 Camera

Looks ok.

As i know, we can directly change some hardware configurations, writing on /sys, so first i found camera path:

Code:

# dmesg | grep -i camera
...
[66449.007123] input: USB 2.0 Camera as /devices/pci0000:00/0000:00:1d.7/usb1/1-3/1-3:1.0/input/input14

Second, search for *led*:

Code:

# ls /sys/devices/pci0000\:00/0000\:00\:1d.7/usb1/1-3/1-3\:1.0/input/input14
capabilities  device  event10  id  modalias  name  phys  power	properties  subsystem  uevent  uniq
# ls /sys/devices/pci0000\:00/0000\:00\:1d.7/usb1/1-3/1-3\:1.0/input/input14/capabilities/
abs  ev  ff  key  led  msc  rel  snd  sw

Found!

Code:

# cat /sys/devices/pci0000\:00/0000\:00\:1d.7/usb1/1-3/1-3\:1.0/input/input14/capabilities/led
0

hummm... may changing to 1 that will turn on.

Code:

# ls -l /sys/devices/pci0000\:00/0000\:00\:1d.7/usb1/1-3/1-3\:1.0/input/input14/capabilities/led
-r--r--r-- 1 root root 4096 Dez 29 12:34 /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3/1-3:1.0/input/input14/capabilities/led

Code:

# chmod +w /sys/devices/pci0000\:00/0000\:00\:1d.7/usb1/1-3/1-3\:1.0/input/input14/capabilities/led

Ok! That is -rw-r--r-- now.

Code:

# echo 1 > /sys/devices/pci0000\:00/0000\:00\:1d.7/usb1/1-3/1-3\:1.0/input/input14/capabilities/led
-bash: echo: write error: Input/output error

WTF?

Trying another way... The uevent special file looks promising:

Code:

# cat /sys/devices/pci0000\:00/0000\:00\:1d.7/usb1/1-3/1-3\:1.0/input/input14/uevent 
PRODUCT=3/c45/62c0/100
NAME="USB 2.0 Camera"
PHYS="usb-0000:00:1d.7-3/button"
PROP=0
EV=3
KEY=100000 0 0 0 0 0 0
MODALIAS=input:b0003v0C45p62C0e0100-e0,1,kD4,ramlsfw

Code:

# echo LED=1 >> /sys/devices/pci0000\:00/0000\:00\:1d.7/usb1/1-3/1-3\:1.0/input/input14/uevent

No fail!

Code:

# cat /sys/devices/pci0000\:00/0000\:00\:1d.7/usb1/1-3/1-3\:1.0/input/input14/uevent 
PRODUCT=3/c45/62c0/100
NAME="USB 2.0 Camera"
PHYS="usb-0000:00:1d.7-3/button"
PROP=0
EV=3
KEY=100000 0 0 0 0 0 0
MODALIAS=input:b0003v0C45p62C0e0100-e0,1,kD4,ramlsfw

But no change too.

That is wrong? There is another way?
I only want to turn on the webcam lights.

roreilly · 01-03-2013, 06:41 AM

What model of camera? Do you have a link to the product page?

Any chance those led's are infrared? If so, you won't see when they are on, but the camera's sensors
will be able to.

aurium · 01-03-2013, 07:31 PM

The cam looks exactly like that: http://sell.lulusoso.com/selling-lea...mera-k038.html ... but that is a common design for webcams.

The box has no reference to the manufacturer or any product detail. The only useful thing on the box is: "driveless camera" and "Support Windows, MacOS and Linux". The cam itself has no number, code or anything written on that.

The LEDs are not infrared. That was my first try.

asaga · 11-25-2016, 07:00 AM

I have a working webcam with a working led, but the led file contains zero even when the light is on.

BW-userx · 11-30-2016, 02:03 PM

2 dollar chinese webcam and you expect it to completely work? I know i would. but... its chinese made cheep webcam.... check the wires inside it. If you have a screw driver to see what you see, I'd take it apart, carefully.