Software Developer. Maker. Amateur Astronomer. Private Pilot.
As you might have noticed the “hcitool lescan” command doesn’t have a timeout argument. This limitation makes the Bluetooth Low Energy scan last forever until a CTRL+C breaks the execution.
To be able to scan for Bluetooth Low Energy devices in range for a given period of time and store the output of the scan in a file I’ve created the following script (lescan.sh):
#!/bin/sh hciconfig hci0 down hciconfig hci0 up hcitool lescan > $2 & pid=$! sleep $1 kill -INT $pid wait $pid
Once you finish successfully building the OpenWRT image following this tutorial you’ll be able to add your own custom packages to the OpenWRT image using the menuconfig tool.
Let’s start by cloning two example Git Repositories I’ve made for this article into the openwrt/package/utils directory
$ cd openwrt/package/utils $ git clone http://github.com/fpfaffendorf/helloworld-c.git $ git clone http://github.com/fpfaffendorf/helloworld-python.git
Continue reading “Installing Your Own Package into OpenWRT By Using ‘menuconfig’”
Set “>” value to PS1 variable to short the prompt,
PS1=">"
http://superuser.com/questions/186743/how-do-i-only-display-the-base-dir-in-my-ubuntu-terminal
Creating an Environment Variable is as easy as running the following commands:
ENV_VAR="Hello World !" export ENV_VAR
In this step by step tutorial I’ll explain how to make the OpenWRT for Raspberry Pi.
In my case I used Oracle VM VirtualBox to virtualize an Ubuntu 14.04 64 bits Operative System. According to OpenWRT Debian Operative Systems are recommended to build the OpenWRT image.
1. Let’s start by installing all necessary tools,
$ sudo apt-get update $ sudo apt-get install git-core subversion mercurial build-essential libssl-dev libncurses5-dev unzip gawk zlib1g-dev
Just run
sudo dpkg-reconfigure keyboard-configuration
… and follow the white rabbit 🙂
To me one of the best sources for sky images. SkyView is a Virtual Observatory on the Net generating images of any part of the sky at wavelengths in all regimes from Radio to Gamma-Ray.
The PPM can be considered a replacement of two preceding catalogs: AGK3 and the SAO Catalog. The PPM Star Catalog effectively replaced these catalogs by providing more precise astrometric data for more stars on the J2000/FK5 coordinate system.
Continue reading “PPM Star Catalog”
In pursuit of developing my own planetary software the first thing I needed to know was how to draw a sphere modelling the sky and how to project the stars on it.
Drawing spheres is simply when using spherical coordinates instead of the cartesian ones.
Continue reading “Mathematically Drawing a Sphere”
NOTE: Nintendo Nunchuk has to be powered with 3v3 only so make sure you use the 3v3 Arduino output. (Arduino DUE owners won’t have to bother about this).
Nintendo Nunchuk is a great and cheap piece of hardware for building robotic applications (and many others) along with Arduino.