http://xkcd.com/196/

A few weeks back i bought a new monitor Dell U2312HM, its a brilliant monitor with support for portrait/landscape switching.
so as it always happens after buying a new monitor i planned a movie night and ran into the screen lock problem, i have set 2 minute timeout for screen lock and some why changing screen settings didn’t work, i knew i had to find a solution and fast or the above xkcd might actually happen with me

so this is what i came up with, having worked with X bindings before for Game-on this was done in under 5 mins (after reading some docs) , another day saved all thanks to Linux, X11 and previous X11 binding experience

This code moves the mouse pointer back and forth every few seconds, which is defined in DURATION

here is the working

Few days back i bought an Arduino UNO board, this is my first Arduino Project and it was damn easy!! I can see the power that Arduino has to offer for hobbyist, i have worked on 8051 and few avr (without Arduino) before, doing stuff with an arduino is pretty easy and straightforward.

In this weekend project i am using a JHD162a (16×2 LCD) connected with Arduino UNO to display the name of the current song being played, i am running mpd on my machine so have used python-mpd to retrieve song info and pyserial to transfer the data over UART to UNO, the UNO just spits out the data received over UART to the LCD.
This is a copy of my earlier project which i did in my third year in college, but that was using a 8051 and i wrote a library (code available here) to control the LCD, currently i am using the LiquidCrystal Arduino library for that.

here is the demonstration

UPDATE -> song name, artist and time also added, video here

PS – you might also want to see the extremely cheap CNC machine being made by one of my friend

The experience at Citrix was great mostly because of the kind of work and guidance i was given, we arrived in Bangalore on 3rd Jan, it was weird that no accommodation was provided to us for the initial weeks, but since manipal is one night journey away from bangalore, we came here after our exams and searched for a flat, we finally decided on a flat in Cambridge Layout (near Indiarnagar) since it was pretty close to our work place which was near brigade road !! I was working with the NetScaler Tools team on a internal stress testing tool called BlackWidow, the best thing about my work at citrix was that i had to work with FreeBSD kernel, which meant i had to use *NIX development tools (cscope/vim/kgdb which is what i am pretty comfortable with) and not some bloated IDE (for me Vim + cscope > any IDE) which i had to learn for my last internship at microsoft, this helped me get started pretty quickly which surprised my mentor, although i was not assigned the feature i wanted to implement still my work was pretty interesting.

I found Citrix to be a really awesome company to work at, it has a lot of interesting products, the people are friendly and helpful and the work culture is great, ohh and not to forget the facilities they provide to employees, but one thing that I noticed during my internship is that the work can become monotonous, so you really need to pitch in and get some interesting work or one might end up doing similar work again and again, but then i think thats the case with most of the places.

The main motive behind me coming to bangalore was meeting interesting people, not that people in Manipal were less interesting, i wanted to meet with some ‘similar’ minded people. I had hardly talked to other people from my college who interned with me, but they turned out be interesting, also interns from other colleges like PeeShit (read PESIT) were interesting. I didnt actually went out to meet people, but then i guess i can do that now as i am going to stay in bangalore. A few days back i met folks at Artoo on their Demo Day, they are doing some really interesting work.

My internship is over but I will be staying in Bangalore for my first full time job, i have a few on campus and off campus offers but more on that some time later, Thanks to my flat mates Mikhail Jacob, Sohil Himanish and Tushar Dadlani for making my stay in Bangalore awesome and Thanks to my mentor, manager, all fellow interns and everyone else at citrix for making my work awesome, you people rock !!

4 mouse cursors on a single screen

few days ago i came upon an article about human computer interactions which mentioned different ways we interact with computes and how we will interact with computers in future, the article instantly reminded me of MPX, now i dont know how many of you remember MPX which enabled interaction of multiple mouse/keyboards in linux. Xserver 1.7 which is used in most of the disto’s was released with MPX, so i decided to find out how to make it work on my existing Fedora 13 box, and using it is pretty simple you just need to use xinput and configure X for multiple input, for that you first need to install xinput, on fedora it is provided by the package “xorg-x11-apps” just do a

[ankur@x144 ankur]# yum install xorg-x11-apps -y

and you are done, for other distro’s i guess there sould be a similar package, after the install we need to find what all is plugged in to the computer, for that we do “xinput list”

[ankur@x144 ankur]# xinput list
⎡ Virtual core pointer                        id=2    [master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer                  id=4    [slave  pointer  (2)]
⎜   ↳ PS/2 Mouse                                  id=14    [slave  pointer  (2)]
⎜   ↳ AlpsPS/2 ALPS GlidePoint                    id=15    [slave  pointer  (2)]
⎣ Virtual core keyboard                       id=3    [master keyboard (2)]
↳ Virtual core XTEST keyboard                 id=5    [slave  keyboard (3)]
↳ Video Bus                                   id=6    [slave  keyboard (3)]
↳ Power Button                                id=7    [slave  keyboard (3)]
↳ Sleep Button                                id=8    [slave  keyboard (3)]
↳ Laptop Integrated Webcam                    id=9    [slave  keyboard (3)]
↳ AT Translated Set 2 keyboard                id=13    [slave  keyboard (3)]
↳ Dell WMI hotkeys                            id=16    [slave  keyboard (3)]

this returns a list of all the input devices, i am running this on my laptop so you can see “AlpsPS/2 ALPS GlidePoint” and “AT Translated Set 2 keyboard” which are my laptop’s mouse and keyboard, to enable multiple keyboard/mouse i will create a group and move my laptops mouse and keyboard to the group,

[ankur@x144 ankur]# xinput create-master main
[ankur@x144 ankur]# xinput list
⎡ Virtual core pointer                    	id=2	[master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer              	id=4	[slave  pointer  (2)]
⎜   ↳ PS/2 Mouse                              	id=14	[slave  pointer  (2)]
⎜   ↳ AlpsPS/2 ALPS GlidePoint                	id=15	[slave  pointer  (2)]
⎣ Virtual core keyboard                   	id=3	[master keyboard (2)]
    ↳ Virtual core XTEST keyboard             	id=5	[slave  keyboard (3)]
    ↳ Video Bus                               	id=6	[slave  keyboard (3)]
    ↳ Power Button                            	id=7	[slave  keyboard (3)]
    ↳ Sleep Button                            	id=8	[slave  keyboard (3)]
    ↳ Laptop Integrated Webcam                	id=9	[slave  keyboard (3)]
    ↳ AT Translated Set 2 keyboard            	id=13	[slave  keyboard (3)]
    ↳ Dell WMI hotkeys                        	id=16	[slave  keyboard (3)]
⎡ main pointer                          	id=10	[master pointer  (11)]
⎜   ↳ laptop XTEST pointer                    	id=12	[slave  pointer  (10)]
⎣ main keyboard                         	id=11	[master keyboard (10)]
    ↳ laptop XTEST keyboard                   	id=17	[slave  keyboard (11)]

above i created a group by the name “main”, you can see a second mouse cursor on screen as soon as you do this, to make both these mouse/keyboard active i will move my laptop’s mouse (id-> 15) and keyboard (id-> 13) to this newly created group

[ankur@x144 ankur]# xinput reattach 15 10
[ankur@x144 ankur]# xinput reattach 13 11

now if i connect an external mouse and keyboard to my laptop i can see both working simultaneously, if you want multiple (more then 2) mouse and keyboards to work, you can create a separate group for them and move them to that group in a similar manner.
after doing this I was not able to find any benefit of using multiple mouse/keyboard on a laptop but it will make sense when you have multi monitor setup and multiple users trying to use the same machine simultaneously.

Here is a video of the android phone (Samsung I5800 Galaxy 3) being used to control a car racing game.

And now the working

After this we decided to work on something which i wanted to finish a long time ago (remember Weekend Project I) so we finished Weekend Project III which is well Weekend Project I + Weekend Project II

And the working of Weekend Project III

Weekend Project III Data Flow

The Data Flow is Phone —-WiFi—-> PC —-USB—-> USB to RS232 Converter —-UART—-> MicroControler —-Relays—-> Toy Car Remote —-RF—-> Toy Car, which is almost same as that of Weekend Project I, except for processing of Sensor Data on Phone.

PS – if you were not able to look at the video’s above they can be found here, here, here and here, also Game On won 2nd prize in Mobi Vision – a mobile application development competition

MobiVision in TextTatva and i dont exactly look like that cartoon depicting me !!

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!

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

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?

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

download here

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