0110.be

Reactie van Gast (14/01/12 - 11:10) op Over 0110.be

Gast — Sat, 14 Jan 2012 11:10:41 GMT

Ff testen

Reactie van Gast (06/01/12 - 01:20) op Order Pizza with USB Pizza Button

Gast — Fri, 06 Jan 2012 01:20:11 GMT

Waar heb je die gekocht?

Android Gingerbread 2.3.4 on LG GT540 Optimus

Joren — Tue, 19 Jul 2011 10:46:41 GMT

I have upgraded the operating system on my LG GT540 Optimus from the stock Android 1.6 to Android Gingerbread 2.3.4. I followed this updgrade procedure.

It is well worth it to spend some time upgrading the phone, especially from 1.6. Everything feels a lot faster and the upgraded applications, e.g. Gallery, are nicely improved.

The main reason I upgraded my phone is to get the open source accessory development kit (ADK) for Android working. I got the DemoKit application working after some time but need to do some more experiments to see if the hardware actually works: I am waiting for a USB Host Shield for Arduino. To be continued…

Athene

Joren — Mon, 23 May 2011 20:58:43 GMT

Athene, Griekenland.

TwinSeats heeft Apps For Ghent gewonnen!

Joren — Wed, 18 May 2011 20:05:23 GMT

Vorige zaterdag werd Apps For Ghent georganiseerd: een activiteit om het belang van open data te onderstrepen in navolging van onder meer Apps For Amsterdam en New York City Big App. Tijdens de voormiddag kwamen er verschillende organisaties hun open gestelde data voorstellen de namiddag werd gereserveerd voor een wedstrijd. Het doel van de wedstrijd was om in enkele uren een concept uit te werken en meteen voor te stellen. Het uitgewerkte prototype moest gedeeltelijk functioneren en gebruik maken van (Gentse) open data.

Luk Verhelst en ikzelf hebben er TwinSeats voorgesteld.

TwinSeats is een website / online initiatief om nieuwe mensen te leren kennen. Met hen deel je dezelfde culturele interesse en ga je vervolgens samen naar deze of gene voorstelling. Door events centraal te stellen kan TwinSeats uitzonderlijke cultuurburen zoeken. Leden vinden die cultuurburen dankzij een gezamenlijke voorliefde voor een artiest of attractie of eender welke bezigheid in de vrijetijdssfeer.

Het prototype is ondertussen terug te vinden op TwinSeats.be. Let wel dit is in enkele uren in elkaar geflanst en is verre van ‘af’, het achterliggende concept is belangrijker.

Samen met Wa Kank Doen van SumoCoders werden we door de jury tot winnaar uitgeroepen. Maandag verscheen er een artikel in de Standaard over AppsForGhent met een vermelding van TwinSeats. Op de Apps For Ghent site is uiteraard ook iets te vinden over TwinSeats ook het juryverslag is er te vinden. Zoals het hoort bij die categorie evenementen werd ook wat afgetweet.

Er is ook een publieksprijs verbonden aan AppsForGhent die wordt over enkele weken uitgereikt.

The Pidato Experiment: Vibrato on a Digital Piano Using an Arduino

Joren — Wed, 13 Apr 2011 12:21:08 GMT

The Pidato experiment demonstrates a rather straightforward method to handle vibrato on a digital piano. It solves the age-old problem on what to do with the enigmatic “vibrato” instructions on some piano solo scores of Franz Liszt. The figure on the right is an exerpt of sonetto 104 del Petrarca.

Since there is no way to perform vibrato on an analogue piano there are all kinds of different interpretations. Interpretations of the ‘vibrato’ instruction include: vibrating the pedal, vibrating the key, simply ignoring it, a vibrato like wiggling with a psychological sounding effect, … A pianist specialized in 19th century music, explains his embodied use of vibrato in a youtube video: Brian Ganz on piano vibrato. Those solutions all seem a bit halfhearted, so I created an alternative approach which resulted in the Pidato experiment.

Pidato is a portmanteau of piano and vibrato, the d, a and o hint to the use of an Arduino. Pidato is also Indonesian for speech, expression. To get a feel of what it actually does I created the video below. Please note that this is a technical demonstration, not an artistic performance… in any way.

The way it works is by translating movement (accelerometer data) to MIDI messages. The hardware consists of an Arduino, MIDI-ports and a three axis accelerometer. The MIDI-ports are provided by this MIDI IN & OUT Arduino shield. The accelerometer is a MMA7260Q from Sparkfun. Attaching the MMA7260Q and the arduino is done by following the instructions here. One change was made: by attaching the 3.3V output to AREF and executing analogReference(EXTERNAL); fluctuations in power supply cease to have an influence on accelerometer data readings. It is represented by the purple wire in the diagram below.

The software should know when a vibrato like movement is made and how to translate such movement to MIDI messages. The software therefore contains a periodicity estimator and frequency detector to detect how periodic a movement is and how fast the movement is repeated. This was done with the YIN algorithm (more commonly used in audio signal analysis). A periodicity threshold was determined experimentally so the system does not yield false positives when playing the piano in the usual way. Another interesting bit of code is the interrupt setup that samples the accelerometer at a fixed sample rate and sends MIDI messages, also at a fixed rate.

MIDI messaging is done over a serial connection. From the Arduino sending a MIDI message is as simple as calling Serial.print with the correct data. For the task at hand (sending vibrato) Pitch Bend messages were used.

The YIN algorithm is encapsulated in a reusable Arduino library and can be used to detect periodicity and frequency for any signal. This guy used his implementation to create a chromatic tuner. The source code for both the Yin Arduino library and Pidato experiment can be found on github or here.

The Pidato experiment was done with the help the friendly hackers at Hackerspace Ghent.

This piano vibrato hack was also covered by hackaday.com and posted to the Hackerspace Ghent blog.

Efeze

Joren — Wed, 02 Mar 2011 19:56:05 GMT

Of Ephesus.

Call for Participation: Newline

Joren — Thu, 20 Jan 2011 10:16:23 GMT

I am a member of Whitespace, a hackerspace in Ghent. It is essentially a loose collective of people with a passion for technology. We will organize an event for our first birthday and hope you will be there. This is our cal for participation:

A newline marks the end of a line and moves the cursor to the next one. One could see it as a sign of progress. A newline gives you a whole new line to be filled. We are happy to announce that we see a newline ahead of us, namely the one that marks the beginning of our second year of existence. Last spring we opened Whitespace and the space has grown in members, projects, usage and infrastructure ever since. To celebrate this, we invite all of you to our first anniversary weekend.

The event is planned for Friday the 25th and Saturday the 26th of March 2011 at Whitespace, Ghent, Belgium. Friday evening will be a social event. Saturday will be a day of talks and workshops followed by a fun activity in the evening.

This is an open invitation to all of you to come to the event and moreover to actively participate by giving a talk or workshop. We are looking forward to all your ideas! We are looking forward to long talks, short talks, hands-on workshops and having an awesome time in our space. Feel like participating? Great! Get it touch with us! We’re interested in all topics, especially if they are a bit out-there.

We want to publish a preliminary program on the 1st of March 2011 and the final program on the 14th of March.

If you want to give a talk or workshop or you want to help us in any other way, please contact us on newline [at] 0×20 [dot] be.

Thank you!

— Whitespace

http://0×20.be/Newline

I will be presenting a talk about fun applications of audio processing.

Find the MAC Address of your Android Device

Joren — Thu, 13 Jan 2011 23:40:56 GMT

Just a quick hint. If you ever need to find the MAC address of your Android device, and who doesn’t, check this file:

/sys/devices/virtual/net/wlan0

You can read the file with the Astro File Manager.

Remote Port Forwarding with Ubuntu 8.04 and OpenSSH 4.7

Joren — Mon, 10 Jan 2011 21:38:30 GMT

With this post I would like to draw attention to the fact that remote port forwarding with OpenSSH 4.7 on Ubuntu 8.04.1 does not work as expected.

If you follow the instructions of a SSH remote port forwarding tutorial everything goes well until you want to allow everyone to access the forwarded port (not just localhost). The problem arises when binding the forwarded port to an interface. Even with GatewayPorts yes present in /etc/ssh/sshd_config the following command shows that it went wrong:

user@local$ssh -R 2222:localhost:22 user@remote
user@remote$sudo netstat -lntp #on the remote server
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp6 0 0 ::1:2222 :::* LISTEN

It listens only via IPv6 and only on localhost an not on every interface (as per request by defining GatewayPorts yes). The netstat command should yield this output:

I do not really know here it goes wrong but there is an easy workaround. By defining both

GatewayPorts yes
AddressFamily inet

in /etc/ssh/sshd_config remote port forwarding works fine but you lose IPv6 connectivity (this due to the AddressFamily setting). Another solution is to use more up to date software: the bug is not present in Ubuntu 10.04 with OpenSSH 5.3 (I don’t know if it is an Ubuntu or OpenSSH bug, or even a configuration issue.

I have been struggling with this issue for a couple of hours and, with this blog post, I hope I can prevent someone else from doing the same.

Oneliner to Install ssh-copy-id on Mac OS X

Joren — Sat, 25 Dec 2010 21:20:54 GMT

ssh-copy-id is a practical bash script, installed by default on Ubuntu. The script is used to distribute public keys. The following oneliner makes it available on Mac OS X:

sudo bash < <( curl —silent http://0110.be/attachment/be.0110/195/install-ssh-copy-id.bash )

This oneliner does three things:

It copies ssh-copy-id from this website to /bin/ssh-copy-id.
It makes sure that ssh-copy-id is executable, using chmod.
There is no three

The install procedure needs superuser rights because it writes in the /bin folder. Executing scripts from untrusted sources with superuser rights is actually really, really, extremely dangerous. But in this case it is rather innocent.

The ssh-copy-id script is the one provided with Ubuntu and Debian, I assume it is GPL’ed. I have not modified it for Mac OS X but it seems to behave as expected. I have only tested the install script and behavior on 10.6.5, YMMV.

How to Develop for LG GT540 Optimus on Ubuntu

Joren — Fri, 17 Sep 2010 20:26:02 GMT

This post describes a crucial aspect of how to connect an android phone, the LG GT540 Optimus, to an Ubunu Linux computer. The method is probably similar on different UNIX like platforms with different phones.

To recognize the phone when it is connected via usb you need to create an UDEV rule. Create the file /etc/udev/rules.d/29.lg545.rules with following contents:

SUBSYSTEM"usb",ATTRS{idVendor}“1004”,ATTRS{idProduct}==“61b4”,MODE=“0666”

On the phone you need to enable debugging using the settings and (this is rather important) make sure that the “mass storage only” setting is disabled.

Rooting the device makes sure you have superuser rights. Installing the android SDK is well documented.

Good luck!

OpenRD - A Low Power Server Running Debian on ARM

Joren — Thu, 05 Aug 2010 10:28:17 GMT

This blog post comments on using the Marvell OpenRD SoC(System on a Chip) as a low power multipurpose home server.

The Hardware

The specifications of the OpenRD SoC are very similar to the better known SheevaPlug devices, so it has 512MB DDR2 RAM, an 1.2GHz ARM processor and 512MB internal flash. To be more precise the OpenRD SoC is essentially a SheevaPlug in a different form factor. The main advantage of this form factor is the number of available connections: 7xUSB, SATA, eSATA, 2xGb Ethernet, VGA, Audio, … which make the device a lot more extendable and practical as a mulitpurpose home server.

The Software

Thanks to the work of Dr. Martin Michlmayr there is a Debian port for the Kirkwood platform readily available. He even wrote a tutorial on how to install Debian on a SheevaPlug. Installing Debian on an OpenRD is exactly the same except for one important detail: the arcNumber variable.

Once Debian is installed you can apt-get or aptitude almost all the software you are used to: webserver, samba, ruby, …

The Alternatives

Sheevaplug
Beagle Board or other OMAP3 SoC’s. The IGEPv2 e.g. has wireless and wired network connections.
Alix system Boards are mostly x86 based.
NSLU2 An ARM platform.

The Future

The next version of the SoC is known as Marvell Armada 310/300

Ijsland

Joren — Wed, 21 Jul 2010 10:24:23 GMT

Ijsland.

Doorhacking: Opening a Door With Your Cellphone

Joren — Thu, 22 Apr 2010 18:08:08 GMT

The problem: There is a group of people that want access to Hackerspace Ghent but there is only one remote to open the gate.

The solution: Build a system that reacts to a phone call by opening the gate if the number of the caller is whitelisted.

What you need:

A BeagleBoard or some BeagleBoard alternative with a Linux distribution running on it. Any server running a unix like operating system should be usable.
A Huaweii e220 or an alternative GSM that supports (a subset of) AT commands and has a USB port.
A team of hackers that know how to solder something togeher. E.g. The hardware guys of hackerspace Ghent.
A python script that reacts to calls.

The Hack: First of all try to get caller id working by following the Caller ID with Linux and Huawei e220 tutorial. If this works you can listen to the serial communication using pySerial and react to a call. The following python code shows the wait for call method:

def wait_for_call(self):
self.data_channel.open()
call_id_pattern = re.compile(‘.CLIP.“\([0-9])”,.*’)
while True:
bytes = self.data_channel.inWaiting()
buffer = self.data_channel.readline(bytes)
call_id_match = call_id_pattern.match(buffer)
if call_id_match:
number = call_id_match.group(1)
self.handle_call(number)

The handle_call method … handles the call.

The second thing that is needed is a way to send a signal from the beagle board to the remote. Sending a signal from the beagle board using Linux is really simple. The following bash commands initialize, activate and deactivate a pin.

echo 168 > /sys/class/gpio/export
echo “high” > /sys/class/gpio/gpio168/direction
echo “low” > /sys/class/gpio/gpio168/direction

Reactie van Gast (21/04/10 - 14:30) op Eindwerk over Beeldschermtechnologieën: LCD, PDP & CRT

Gast — Wed, 21 Apr 2010 14:30:59 GMT

thx

Jobsopschool.be beter beveiligd

Joren — Sun, 18 Apr 2010 10:27:38 GMT

Omdat er op jobsopschool gevoellige informatie te vinden is (bijvoorbeeld C.V.’s van kandidaten) is de beveiliging ervan belangrijk. Om die veiligheid te garanderen werd de vacaturesite voor onderwijzers op een volledig dichtgetimmerde aparte virtuele server geplaatst. Een server met enkel de broodnodige software zorgt voor een veilige en snelle afhandeling van requests.

Ook werd er voor gezorgd dat alle verkeer versleuteld wordt via SSL. De lighttpd webserver server werd geconfigureerd met deze tutorial die de configuratie van lighttpd met SSL bespreekt. Er werd een SSL certificaat van godaddy aangekocht omdat het root certificaat van godaddy in zowat alle browsers aanwezig is en omdat ze een redelijke prijs vragen.

Reactie van Gast (13/04/10 - 20:00) op SQL-bestand met een lijst van alle Belgische postcodes en steden

Gast — Tue, 13 Apr 2010 20:00:57 GMT

Dan maak je gewoon een functionele index aan, dan wordt de bewerking niet uitgevoerd in je query, maar is al voorbewerkt in de index. En dus wordt bij het sorteren een index gebruikt.CREATE INDEX idx_naam ON tabelnaam (translate(structure, ' ', 'z'));

Caller ID with Linux and Huawei e220

Joren — Sun, 11 Apr 2010 18:09:13 GMT

This is the scenario: you have a Huawei e220, a linux computer and you want to react to a call from a set of predefined numbers. E.g. ordering a pizza when you receive a call from a certain number.

The Huawei e220 supports a subset of the AT commands, which subset is an enterprise secret of te Huawei company. So there is no documentation available for the device I bought, thanks Huawei. Anyhow when you attach the e220 to a Linux machine you should get two serial ports:

/dev/ttyUSB0
/dev/ttyUSB1

To connect to the devices you can use a serial client. GNU Screen can be used as a serial client like this: screen /dev/ttyUSB0 115200. The first device, ttyUSB0 is used to control ttyUSB1, so to enable caller ID on te Huawei e220 you need to send this message to ttyUSB0:

AT+CLIP=1

To check for calls you should listen to ttyUSB1. A serial session for ttyUSB1 looks like:

^BOOT:44594282,0,0,0,6
^RSSI:18
RING
CLIP: "33499311152",145,,,,0
^BOOT:44594282,0,0,0,6

The RING and CLIP messages are the most interesting. The RING signifies an incoming call, the CLIP is the caller ID. The BOOT and RSSI are some kind of ping messages. The following Python script demonstrates a complete session that enables caller ID, waits for a phone call and prints the number of the caller.

#!/usr/bin/env python
import serial, re

command_channel = serial.Serial(
port=‘/dev/ttyUSB0’,
baudrate=115200,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
bytesize=serial.EIGHTBITS
)
command_channel.open()
#enable caller id
command_channel.write(“AT+CLIP=1” + “\r\n”)
command_channel.close()

ser = serial.Serial(
port=‘/dev/ttyUSB1’,
baudrate=9600,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
bytesize=serial.EIGHTBITS
)

ser.open()

pattern = re.compile(‘.CLIP.“\([0-9])”,.*’)

while 1:
buffer = ser.read(ser.inWaiting()).strip()
buffer = buffer.replace(“\n”,"")
match = pattern.match(buffer)
if match:
number = match.group(1)
print number

YIN Pitch Tracker in JAVA

Joren — Fri, 09 Apr 2010 14:07:04 GMT

To make Tarsos more portable I wrote a pitch tracker in pure JAVA using the YIN algorithm based on the implementation in C of aubio. The implementation also uses some code written by Karl Helgasson and Teun de Lange of the Jazzperiments project.

It can be used to perform real time pitch detection or to analyse files. To use it as a real time pitch detector just start the JAR-file by double clicking. To analyse a file execute one of the following. The first results in a list of annotations (text), the second shows the annotations graphically.

java -jar pitch_detector_yin.jar flute.novib.mf.C5B5.wav
java -jar pitch_detector_yin.jar —file flute.novib.mf.C5B5.wav

The provided flute sample is from The Musical Samples library of the University of Iowa and converted to mono wav. The source code of the pitch tracker can be found below.

Reactie van Gast (21/03/10 - 17:33) op Order Pizza with USB Pizza Button

Gast — Sun, 21 Mar 2010 17:33:28 GMT

i'd find it more usefull if you could get it to work on openwrt using package/shellscripts without too much big libraries

Reactie van Gast (12/03/10 - 14:06) op Rotel RA-812

Gast — Fri, 12 Mar 2010 14:06:31 GMT

een half jaar geleden heb ik er een op de vlooienmarkt opgevist 40 euro. De beste 40 euro die ik in tijden heb besteed. Met een stel Dali's erop aangesloten heeft hij een natuurgetrouwe weergave en een mooie verdeling over het toonbereik.

Boids 3D with Processing

Joren — Fri, 22 Jan 2010 17:48:21 GMT

Reactie van Gast (18/01/10 - 16:56) op Zelf een devilstick maken

Gast — Mon, 18 Jan 2010 16:56:20 GMT

Hoelang moeten die kleine stokjes zijn?

Reactie van Gast (28/11/09 - 16:35) op Zelf een devilstick maken

Gast — Sat, 28 Nov 2009 16:35:42 GMT

Echt bedankt! Wrkt Perfect!