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Stuff
Weekend Project II
Aug 29th
In march i posted about a weekend project which involved controlling a small toy car using my cell phone, this is a similar one again implemented in few hours, here we are trying to play the awesome game of pong using the tilt sensor on Samsung Wave. The pong application running on Laptop is written in Qt (C++) and the application on the Phone is written using the Bada SDK.
The working is simple, the pong application running on Laptop requires phones to make a TCP connection to it. Phones just create a TCP connection to the application on PC and sends tilt sensor data to it, movement of paddles is done by the PC application based on the value it receives from the phones. It still requires better calibration and we will work on it after the exams are over (Education prevents you from doing cool things!!), there are a lot of ideas buzzing in our empty heads (according to our teachers!!) , the original idea was by Abhimanyu which we implemented.
if you cannot see the above video here and here are short demo of how it works.
PS – code and proper working for the previous and this weekend project will be posted soon!
Weekend Project
Mar 11th
In Dec 2009 at foss.in at the maemo stall i saw a guy control a small toy car through accelerometer on his N900, i thought of replicating that but it just remained in my mind, so last Saturday i finally decided to implement it and went straight to a toy store and bought a toy RF car, one hour of hacking and i was able to control the small car through by phone (Nokia E61i) here is the video of it working.
the concept is simple, i send commands through my phone over wifi to my laptop which controls the car remote, controlling a toy car remote is very easy with a Parallel port and few transistors but laptops don’t have parallel ports, so i used a micro-controller in between to sort that out, so now micro controller controls the car remote by acting on signals received over UART from laptop.
the working is Phone —(WiFi)—>Laptop —(USB/UART)—> Micro controller —(Relays)—> Car Remote —(RF)—> Toy Car
will post details with code sometime later
strange thing in python
Feb 10th
i recently noticed this anyone has a proper explanation for this
for literals i get this
>>> def a():
... b = []
... c = {}
...
>>> import dis
>>> dis.dis(a)
2 0 BUILD_LIST 0
3 STORE_FAST 0 (b)
3 6 BUILD_MAP 0
9 STORE_FAST 1 (c)
12 LOAD_CONST 0 (None)
15 RETURN_VALUE
but for constructors i get this
>>> def a():
... b = list()
... c = dict()
...
>>> dis.dis(a)
2 0 LOAD_GLOBAL 0 (list)
3 CALL_FUNCTION 0
6 STORE_FAST 0 (b)
3 9 LOAD_GLOBAL 1 (dict)
12 CALL_FUNCTION 0
15 STORE_FAST 1 (c)
18 LOAD_CONST 0 (None)
21 RETURN_VALUE
i mean why the difference, i was thinking {} and dict() do the same thing, shouldn’t they?
Begining Python workshop
Jan 27th
LUG Manipal python workshop poster
LUG Manipal is organising a workshop on python, Workshop is aimed at people interested in beginning programming with python.No programming experience required.
Details are ->
Time: 5:30 pm
Place: NLH 103
Date: 29th JAN to 3rd FEB
PS :- Slides for the workshop are available Begining Python Slides
Mobi Vision 2.0 Slides
Oct 15th
First and Second Phase for MobiVision 2.0 is long over, and we can call it a workshop well done, the slides are here
Mobi Vision 2.0
View more documents from Ankur Shrivastava.
A simple python socket chat example
Jul 30th
i was trying to explain sockets to one of my friend and this is what i used, the code should be self explanatory, this is a very simple application of sockets…
download here
Creating your own service like tinyurl
May 24th
Few weeks ago i came across this article on Techcrunch which says tinyurl is worth $46Million (of course before twitter started using bit.ly as default) which made me think how hard is it to make a simple service like tinyurl and i figured out its not hard. so i used apache’s mod_rewrite to rewrite the url and forward the code to a php script ( url.php ) which will then search for the url in database and take the use to the original url and for shorting, url it is inserted into a table with a auto increment primary key and the key is converted to base36 which contains [a-z] and [0-9], making the short code…
First create a database say ‘shorturl’
CREATE TABLE IF NOT EXISTS `shorturl` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`url` varchar(300) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;
then create file .htaccess where you want your url to be and write
RewriteEngine On
RewriteCond %{REQUEST_URI} \/([0-9a-z]*)$ [NC]
RewriteRule ^(.*) url.php?url=%1 [L]
and to create the url we will use a simple file say create.php
<html>
<head>
<title>Url Shortner</title>
</head>
<body>
<?php
ob_start();
$host=""; //host
$dbuser=""; // database username
$dbpass=""; // database password
$db=""; //database name
$con = mysql_connect($host,$dbuser,$dbpass);
mysql_select_db("url",$con);
if (!isset($_POST['shorten']))
{
echo "<center><h3>Enter the url to shorten</h3><form method='POST'><input type='text' name='url' />
<input type='submit' name='shorten' value='Shorten' /></form></center>";
}
else
{
if (isset($_POST['url']))
{
$url=" ".mysql_real_escape_string($_POST['url']);
if (strpos($url,"http://") or strpos($url,"https://") or strpos($url,"ftp://"))
{
$url=mysql_real_escape_string($_POST['url']);
}
else
{
$url="http://".mysql_real_escape_string($_POST['url']);
}
$q="select * from url where url='{$url}'";
$res = mysql_query($q,$con);
$row=mysql_fetch_row($res);
if (!$row)
{
$query="insert into url set url='{$url}'";
$res = mysql_query($query,$con);
}
$query1="select id from url where url='{$url}' limit 1";
$res=mysql_query($query1,$con);
$row=mysql_fetch_row($res);
echo "shortened url is http://yoursite.com/".base_convert($row[0],10,36);
}
}
ob_end_flush();
?>
</body>
</html>
then our url.php file
<?php
ob_start();
$host=""; //host
$dbuser=""; // database username
$dbpass=""; // database password
$db=""; //database name
$con = mysql_connect($host,$dbuser,$dbpass);
mysql_select_db($db,$con);
if (isset($_GET['url']))
{
$query="select * from url where id ='".base_convert(mysql_real_escape_string($_GET['url']),36,10)."'";
$res = mysql_query($query,$con);
$row=mysql_fetch_row($res);
header("Location: ".$row[1]);
}
ob_end_flush();
?>
Download here
JavaFX and Pong
Mar 1st
There was a workshop conducted by engineers form SUN in our college regarding JavaFX, which went quite well. I was planning to start with JavaFX but as there was no Official release of any Linux SDK, it kept me back but this semester i had to install Windows because of my University which wants me to use Visual Studio for my mini project this semester, so as i had Windows (unwillingly) on my system i planned to go and attend this JavaFX workshop.
From what i have learned in these two days, JavaFX looks promising for developing Rich Internet Applications, the language is somewhat a mixture of JavaScript and Java. With Type Inference , Audio/Video support etc making it very easy to use and create applications with.
In the workshop after every thing was over we were asked to make a simple application in JavaFX, so here is my code for a Simple pong game in JavaFX
the resolution is set to 1440×900 you can change it to your resolution in the code
More >
HowTo MPD with Pulse audio
Feb 13th
A Little background, i just shifted to mpd from Amarok 2.0 somewhy i dont seem to like Amarok 2 but thats a different story, For those who dont know MPD s a flexible, powerful, server-side application for playing music. which runs as a daemon and has a lot of front ends for it, Sonata being a popular one.
now coming to the point i use Fedora 10 and it has Pulseaudio by default, now the problem is i some time get “NO Read Permission” in Sonata and then mpd would stop working, in mpd.log file i will find “Error opening ALSA device “hw:0,0″: Device or resource busy” error, which means this is an pulseaudio permission issue, to solve it we need to change the mpd.conf (/etc/mpd.conf) to
audio_output {
type "pulse"
name "My Device"
device "hw:0,0" # optional
format "44100:16:2" # optional
}
then we need to add
load-module module-native-protocol-tcp auth-anonymous=1
to /etc/pulse/default.pa which gives everybody permission to use pulseaudio and thats it.
LUG Manipal’s Python Workshop
Jan 26th
Python Workshop Poster
LUG Manipal is organising a workshop on Python, which is a dynamic object-oriented programming language that can be used for many kinds of software development. It runs on Windows, Linux/Unix, Mac OS X, OS/2, Amiga, Palm Handhelds, and Nokia mobile phones. It comes with extensive standard libraries, and can be learned in a few days.
The workshop requires no prerequisites, even knowledge of C is not required, it is aimed at people interested in beginning programming with Python.
There is no charge for the workshop and no registration is required, everyone is invited.
People using Windows are requested to Install the Following Software before coming to the workshop
1) Python 2.6.1 from here
2) Notepad++ from here
Note: These will also be distributed on the first day of the workshop, If you are not able to install/download them you can get them there…
