Page 360 - Hacking Roomba

Chapter 15 — RoombaCam: Adding Eyes to Roomba 341

Installing Drivers
Similar to the USB serial adapter installation, two drivers must be downloaded and installed.
The first is the generic video device driver, called videodev.The second is spca5xx_lite.The
steps to get and install the drivers are:
root@OpenWrt:~# ipkg install videodev
root@OpenWrt:~# wget
http://roombahacking.com/software/openwrt/spca5xx_lite.o.gz
root@OpenWrt:~# gunzip spca5xx_lite.o.gz
root@OpenWrt:~# mv spca5xx_lite.o /lib/modules/`uname -r`
root@OpenWrt:~# insmod videodev
root@OpenWrt:~# insmod spca5xx_lite
root@OpenWrt:~# echo “videodev” >> /etc/modules
root@OpenWrt:~# echo “spca5xx_lite” >> /etc/modules

As before, the insmod commands load the drivers immediately. Adding the driver names to
/etc/modules causes the drivers to be loaded on reboot. With the drivers installed, plug in
the webcam and watch the output of dmesg. You should see the driver recognize the camera.
For the camera shown in this example, you see:
root@OpenWrt:~# dmesg
[...]
usb.c: registered new driver spca5xx
spca_core.c: USB SPCA5XX camera found. Type Creative Instant P0620
spca_core.c: spca5xx driver 00.57.06LE registered

Taking Pictures
The driver creates a standard Video For Linux (v4l) device, so you could use any v4l program.
But the easiest way to start capturing images is to get the spcacat program, from the author
of the spca5xx driver. The program expects devices to be in /dev, not in a subdirectory, so a
symlink (also known as a symbolic link, a file that points to another file) needs to be created.
root@OpenWrt:~# wget
http://roombahacking.com/software/openwrt/spcacat.gz
root@OpenWrt:~# gunzip spcacat.gz
root@OpenWrt:~# chmod +x spcacat
root@OpenWrt:~# mv spcacat /usr/bin
root@OpenWrt:~# ln -s /dev/v4l/video0 /dev/video0
root@OpenWrt:~# spcacat -d /dev/video0 -g -f jpg -p 1000 -o
You can run spcacat with no arguments to see what its options are. The notable ones being
used here are:

-f jpg: Data format is JPEG stream from camera.
-p 1000: Pause 1000 milliseconds between images.
-o: Overwrite image. Output image is SpcaPict.tif and is overwritten each time.