Author Archives: anand.dersingh@gmail.com

Raspberry Pi – hiding boot messages on screen

There may be a time when one would want to hide boot messages that show up on the screen (or monitor or TV). The trick is to edit /boot/cmdline.txt file.

One may use the following command

sudo nano /boot/cmdline.txt

Then make the following changes to the file:

- Replace "console=tty1" by "console=tty3" to redirect boot messages to the third console.
- Add "loglevel=3" to disable non-critical kernel log messages.

After changing, to get to the console simply press Alt + F3 during or after boot. However, if text cursor needs to be hidden also then add “vt.global_cursor_default=0” to the /boot/cmdline.txt file. In my case, I prefer to have text cursor as an indicator that it is actually booting.

Here is the content of my /boot/cmdline.txt

dwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty3 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait logo.nologo loglevel=3

Information in this page is taken from http://www.raspberrypi.org/phpBB3/viewtopic.php?t=13807&p=153177

Setting up Wifi (EDIMAX) on Raspberry Pi

This post is adapted from http://kerneldriver.wordpress.com/2012/10/21/configuring-wpa2-using-wpa_supplicant-on-the-raspberry-pi/

First you need to see if the EDIMAX usb Wifi is recognized by using command

lsusb

Once you see the device connected, edit the file /etc/network/interfaces (requires root)

....

auto wlan0
allow-hotplug wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf

iface default inet dhcp

Then edit /etc/wpa_supplicant/wpa_supplicant.conf (requires root):

network={
    ssid="Your SSID Here"
    proto=RSN
    key_mgmt=WPA-PSK
    pairwise=CCMP TKIP
    group=CCMP TKIP
    psk="YourPresharedKeyHere"
}

After that, you will need to bring up the “wlan0″ interface using “ifup” (requires root):

$ sudo ifup wlan0

You may see the following messages like this:

ioctl[SIOCSIWAP]: Operation not permitted
ioctl[SIOCSIWENCODEEXT]: Invalid argument
ioctl[SIOCSIWENCODEEXT]: Invalid argument

You may ignore the messages but the adapter should be usable now

Installing debian package (nano) on FriedlyArm (Arch Linux with QT)

I am a fan of nano editor and somehow FriendlyArm does not come with it. The following is a script which I use in installing nano

wget "http://ftp.tw.debian.org/debian/pool/main/n/nano/nano-tiny_2.2.4-1_armel.deb" 
wget "http://ftp.tw.debian.org/debian/pool/main/s/slang2/libslang2_2.2.2-4_armel.deb" 
FILES=$(ls /root/*deb)
cd /
for NAME in $FILES ; do
     ar -x "${NAME}"
     tar zxf data.tar.gz
     rm debian-binary data.tar.gz control.tar.gz
     rm "${NAME}"
done
cd –
ln -sf /bin/nano-tiny /bin/nano

Note: copy the content of extracted lib to /lib also
 

Building and installing wxPython 2.9.4.0 on Raspberry Pi (Raspbian)

As of writing the official release of the wxPython is version 2.8 which one could use apt-get install:

sudo apt-get install python-wxgtk2.8 python-wxtools wx2.8-i18n libwxgtk2.8-dev libgtk2.0-dev

However, in my case, I need to use the WebView and it is available in version 2.9. This is the reason why I have to build and install wxPython 2.9.4.0 from source.

Download and Patch Source

cd ~
wget "http://downloads.sourceforge.net/project/wxpython/wxPython/2.9.4.0/wxPython-src-2.9.4.0.tar.bz2"
wget "http://downloads.sourceforge.net/project/wxpython/wxPython/2.9.4.0/wxPython-src-2.9.4.1.patch" 
tar xvjf wxPython-src-2.9.4.0.tar.bz2
patch -p 0 -d wxPython-src-2.9.4.0/ < wxPython-src-2.9.4.1.patch
mkdir wxPython-src-2.9.4.0/bld

Install Dependencies

sudo apt-get install dpkg-dev build-essential swig python-dev libwebkit-dev libjpeg-dev libtiff-dev checkinstall freeglut3 freeglut3-dev libgtk2.0-dev  libsdl1.2-dev libgstreamer-plugins-base0.10-dev libgstreamer0.10-dev libgconf2-dev libglapi-mesa libosmesa6 libglu1-mesa-dev libglu1-mesa mesa-common-dev

Note that I install mesa as well since wxPython requires OpenGL and mesa packages include OpenGL headers. Also, some packages above may not necessary but I install then since I was not sure.

Build and Install

This step takes hours (~8 hours).

cd wxPython-src-2.9.0.1/wxPython
python build-wxpython.py --build_dir=../bld --install

Note: make sure that python command that you use matches the version of the python that you are planning to use with wxPython. You may check the version by

python -V

Final Touch

The wx modules are placed under /usr/local/lib but when I run demo.py it does not recognize wx since modules were misplaced. I copy all the wx modules under /usr/local/lib to /usr/lib

sudo cp /usr/local/lib/libwx_*  /usr/lib

Now you can try the demo under

python demo/demo.py