BlaXwan's

Multitouch Display: CD burner infrared laser short test

2008-06-15T22:51:48Z

This is a very short post compared to the ones that I write normally.

Anyway, I was looking around to find how I can achieve the great results that AlexP got in his laser multitouch. I really suggest you to read that link, Alex method is really cool!

So, basically I was guessing where I could find a suitable infrared laser to use for generating a very thin flat plane of infrared light just in front of the multitouch screen.

Googlin' around I found that the laser included in the DVD player/burner is not good as it is a visible red laser of about 650 nm of wavelenght. But the CD player/burner has a chance to be ok as it should be around 780 nm which is just below the visible spectrum that ranges from 380 nm (violet) to 750 nm (red).

Luckily I had an "ancient" SCSI CD burner in my drawer so, of course, I embraced my screwdriver and took it apart.

I was very happy to discover that I can't see anything coming out from the laser with my bare eyes but, once I looked at it with the infrared enabled camera that I use for the multitouch I saw a bright, coherent orange light!

I shoot a very short video:

So, it seems that the laser is really an infrared one. Now next steps may be to collect enough informations on it regarding its real frequency and power.

Further steps will be to understand how to drive it correctly, building a small voltage and current limiter circuit that may power it up without burning it.

Last steps, hopefully, may be to understand how I can get a cylindrical lens without dismantling a craftsmen leveler...
:o)

Multitouch Display: a plexiglas case for the LCD FTIR multitouch (part two)

2008-06-08T22:02:11Z

Look at this, isn't it wonderful?!?!

Yessss!!! It looks very very nice!
Anyway, of course it is still to be completed, I need to prepare all the braces for the circuit boards, the bracket for the webcam and, of course the infrared setup and the front mask.

So, let's start with this second part of the construction notes!

After bending all the parts, I had to refine them because, as I said, I abounded with measures because I was not knowing how much material I would loose with the bend. In this phase I discovered how useful is the circular saw for the Dremel instead of the electric hacksaw that I used to cut the parts before. The advantage of the circular saw is that it can make very straight cuts and you will have better result.

So, basically I cut again quite all the sides of all pieces of plexiglas refining them to the right size, then I started to try to put all together and see what was needing to be accomodated.

Once I got the situation where all pieces were complying well together I started with the holes for the screws. As I said in the previous post, I decided for the most difficult assembly solution: screws on the edge of the plexiglas.

There was a lot of difficulties: the first one is to keep the drill parallel to the edge all along the hole just using the hands, the second one may be to drill the hole without melt or break the polystirene ecc. Other than these issues, I had also a lot of oblique sides that means oblique holes!

I have to admid that it was really taugh but, luckily I had good results. I used a 1,5 mm drill bit for 2 mm screws. I made a lot of tests on spare polistyrene pieces to understand how I could drill it without melting it. At the end of the game I decided to don't care about the melting plastic!

I just regulated the Dremel to the slowest speed and made all the holes keeping the Dremel in position just by hand.

As last step, I refined all the edge sanding them with fine-grained sand paper and a little bit of polish in order to have smooth edges.

That's all folks!

In the next days I should have time to go on with the bracket for the webcam and all the infrared stuff for the FTIR.

To be honest I put on hold the order that I prepared for the IR LEDs, this is because I saw this great post from AlexP that is changing everything. Basically he is not using any plexiglas for the FTIR but he was able to spread the IR light from a laser into a flat surface with a cylindrical lens! Great idea!

With this method his multitouch display is able to detect a finger just befoure (1 mm) it touches the panel so to achieve a "zero force" touch!

I'm totally fascinated by this idea and I'm actually thinking about to change on the fly my project and order a IR laser LED instead of the "normal" IR LEDs that I was ordering, as well I would not use any plexiglas for the FTIR.

I'll update you ASAP, stay tuned!

Multitouch Display: a plexiglas case for the LCD FTIR multitouch (part one)

2008-06-02T22:28:44Z

As you surely remember, three weeks ago I posted about my first test with an LCD panel for multitouch applications. I saw that it had enough chances to work out but I was so scared about the fact that the bare LCD panel is extremely delicate. So, as I was saying at the end of the post, I started to think, then work, to a case for this multitouch display.

Of course I thought about a case that should also look nicely, what's better than a plexiglas one?

So, after some weekends of work, this is how the case is looking today:

I designed it trying to keep its size as small as possible, so I went for a cut pyramid shape. The pyramid is (or better, it should) be deep enough to hold the webcam in a position that, using the wide angle optics, is far enough to capture the entire screen view.

I can honestly say that probably I choose a very complex shape to build, infact it took me several days to bring it to this stage. For this reason I'll talk about how I proceed and I think that this will fill at least 2-3 posts. Let's start!

First of all, reading also several modding forums, I undestood that plexiglas is quite difficult to work so I choose a similar material, the transparent polystyrene. It seems more tollerant to mistakes even if it is more easy to melt while working with electrical tools like drill or saw.

Anyway, all begins with a good drawing scheme of the whole case and the pieces that needs to be cut. I paid big attention in this trying to consider every factor like angles because there are very few square angles in my design, and exact polystyrene sheet thickness.

In addition, there are some bends in my design and I was not knowing how much material the bend was taking, so, basically, I was abounding with measures (3-5 millimeters more) impacted by bends and I considered to cut again the parts after bending them.

I used the electric hacksaw for cutting the polystyrene sheet but, keep in mind that it tend to melt very easily. So, to avoid that, I used a dimmer to regulate at very low speed the saw. Let's say a 2 saw movements per second under load. This useful also to be very accurate in cutting following a straight line.

I know, every single sencond that you spend working this kind of material you are tempted to take away the protective film but, I can say that it is very important to keep it on until the very end. In bad cases keep it in place with adhesive tape but don't remove it!

Then I cut some pieces of wood to use as mold for bending the pieces of polystyrene. Then I used those pieces to build a complete mold for every piece. It was a little bit of work more but absolutely essential to have a precise bent shape.

Once I had the molds, I started to heat the polystyrene. I used a heat gun, one of that tools that are useful to remove the paint. Basically it is a sorta like of hairdryer with a high temperature airflow.

I used it very gently, moving it very often, slowly but constantly to avoid any break in the plastic sheet. Despite this, one of the pieces broke and it was the last one (of course)!

The polystirene sheet that I used was 5 millimeters thick and it took about 2-3 minutes with the heat gun to soften enough.

When it was ready I gently pressed it on the mold and I used other wood sheet and small morsel to keep it in place. The polystyrene needs another 3-5 minutes to cool down enough to be hard again and, with the morsels it could take all the time it needs.

I paid particular attention to the angles. In order to have clear ones I used pieces of wood to press the polystyrend exactly on the edge.

I can say that the more you heat up evenly the polystyrene sheet, the best bending results you will have.

The last step that I will show in this post is regarding the piece for the back and bottom of the case. It was the most difficult one because it had two bends. Of course I had to create an ad-hoc mold just for it.

I'll continue to illustrate the case building process in the next posts, stay tuned!

New high-torque servo for the robotic arm

2008-05-19T22:01:43Z

As you probably already read about, I got performance problems with my robotic arm.

The issue is the relatively high weight of the arm itself compared to the poor torque performance of the cheap servos that I used. So, last week I finally decided to buy new servos for my robotic arm:

I got them bidding on eBay. Basically I wanted to buy two Towerpro MG995R that is a compact but powerful servo, with metal gears that should be capable of 10 Kg/cm.

While looking for them, I saw also the Towerpro 9805BB that shows a great value of 20 Kg/cm of torque in its features.

As the price was really low (mostly because the bid was just started) I offered the minimum which was 11 euros.

Probably I was really lucky because nobody else bidded on it so I got it for 11 euro instead of the 25 of the "buy it now" price!

This powerful servo is amazing big compared to normal ones like the MG995R.

So, now I have 10+10 Kg/cm for the two MG995R and 20 Kg/cm for the 9805BB.

This way I'll have to chose whether to use the two small one for the shoulder and the big one for the elbow (most probably) or the reverse.

Unfortunately for using those new servos I need to build again several parts of the robot, at least the shoulder servo brackets, the arm and forearm.

Anyway, even if with lower priority than my new LCD multitouch display work, I hope to find time in the next weeks to design the new parts in order to have again a fully functional and more powerful robot arm, stay tuned!

Multitouch Display: testing LCD screen panel for FTIR

2008-05-12T22:13:50Z

Quite a long time has passed since I did something more for my multitouch display. My last post on this topic was on November!

Unfortunately I did not any progress basically because I don't own a projector, so, everytime I should ask to someone to lend me a projector then I have limited time to do some tests with it. This is not exactly comfortable especially because I have very limited spare time and quite never in consecutive days.

So, in the last months, I was thinking more often that it would be nice to achieve the goal to use an LCD instead of a projected screen.....and I started to do it!

To be honest, I thought about using an LCD for a multitouch display since the very first moment. Infact, when I bought the webcam, the Fire-i from Unibrain, I bought also a wide angle, non IR coated lenses for the cam. This was exactly because I thought that, if all things worked out I could try with LCD and use the wide angle lenses to have a short distance beetween the camera and the display itself.

Ok, I was a little bit optimist at the first time but....at the end of the game it was definitively good!

Some days ago, at work, I was speaking with a great new colleague, Pietro, who read this blog and discovered all the works that I've done at home. I was very pleased to talk with him illustrating all the hints and techniques used with the multitouch display. Then I said "yes but I don't have a projector, actually I'm thinking about to buy an old used 14" LCD on eBay to sacrifce for the experiment". He had a great answer: "I have one abandoned in my cellar, I may give it to you"!!!

He was so gentle to give me this great LCD monitor for free!

G R A Z I E P I E T R O ! ! !

So, last weekend, I started to disassemble the monitor to get out the bare LCD panel and test it with the infrared camera and the IR LEDs.

I was really surprised of how many pieces there were in the monitor! Kilos of screws, panels, the speakers in the basement, plastic covers and supports...

It took me more than two hours to fully disassemble it, especially because I didn't wanted to break something so I was very gentle trying to have a safe and, hopefully reversible, disassembling. At the end I had the bare LCD monitor panel and a little fear that this was a non-return point because I already forgot how to reassemble the monitor :o)

Of course the first step was to carefully inspect the backlight complex and its filters to understand what needed I needed to remove in order to have a monitor transparent to IR but not so transparent to the visible light (I need the backlight anyway to see the monitor image!).

I think I was really lucky because I needed to remove only the reflective white sheet that was in the back of the backlight, I kept the Fresnel lens and the diffuser. If I will have time I'll post some pictures of those layers for those of you that wants to understand exactly what I'm talking about.

Then I immediately put the LCD panel on the desk (keeping it vertical by two Fonera boxes :o). I reconnected all the electronics, double-checking the connections in order to be sure not to burn out the monitor on the first test. But, very soon, I realized that, even if the panel worked out, I could have a serious problem.

The problem is in the Flat Flex Cable (FFC) that is connecting the board on the right side of the display with the board on the bottom side. It is really too short and requires that both boards sits in the back of the panel, without the possibility to bend the boards out to free the view of the entire display surface from the back.

Anyway, I didn't care at that moment and switched on the monitor....all ok, it was still working!
Then, second test, I put the IR webcam on the back of the LCD and tested the IR remote of the TV: wow, I saw its IR light!

In addition the LCD didn't lost too much brightness with the removal of the reflective white sheet and the image was still clearly visible.

My last test was with a couple of spare Osram SFH485P IR LEDs that I had from my first multitouch: all ok, I was able to see very very clearly them by the webcam through the LCD display and I was able also to see the IR light reflected by my fingers. I took this as the definitive evidence that this setup could work greatly.

So, scared by the risk to break the very thin and delicate LCD panel, I put it apart in a safe place. I started to think about a good box to hold all the things together safely and steadily.

While brainstorming for the box, I found a great site that was selling spare parts for video projector and.....YES! On that magic site I found the right FFC extension! So the problem was solved!

I hope to post some news on this exciting new adventure very soon!

Stay tuned!

Reflashing a WRT54G with JTAG (my debricking experience)

2008-04-16T20:22:27Z

Some days ago, in my office, we had to reorganize our spaces and change our desks. It was also the chance to scrape out some stuff from our lockers. So, I noticed that one of my colleague was trashing a brand new Linksys WRT-54g! Of course I was asking why she was getting rid of it and the answer was "it's broken, it could not be repaired, they tried also resetting the hardware but there's no way". I kindly asked if I could have it and try to repair it.

This way I won the chance to have a great wireless router for free, or to have some hundred grams of rubbish if I was not able to fix it. Good challenge, I was happy anyway :o).

Before taking it I tried to switch it on and I saw that some LEDs were on (so there was at least something working) and, on top of all, that WAN and LAN LED behaviour was changing after some seconds. This was meaning that there were some working circuits and, most probably, the processor was unsuccessfully attempting to load something. Reading though forum posts and debricking guides I understood that my blinking power LED was confirming my suspects.

I understood that there was an unsuccessful attempt to upgrade or change the firmware. So, luckily, it was not hardware failed but just "bricked"!

As you may know, last year I worked a lot with OpenWRT on the Fonera, so I already heard about low level re-flashing this kind of devices through a so called JTAG cable.

So I went straight on searching more informations about this method and how I could accomplish it. I found the great guide from HairyDairyMaid (aka LightBulb). This guide is very famous and it gives all the needed informations to complete the job, that's why I'm not trying to write down a tutorial about this.

On the other hand I found few resources showing how to proceed practically, so my intention is to give my 2 cents illustrating with some photos and (hopefully) useful hints about how I managed to fix my WRT router.

I used the unbuffered version of the JTAG cable. It is a damn simple circuit, so simple that you need just 4 resistors and a DB25 male parallel port connector and, of course, a PC.

I bought the four resistors thinking to find a DB25 connector at home. Unfortunately I had no spare connectors so I had to take out it from another flashing cable.
It was an old LanC cable that I made to hack a Sony camcorder in order to enable the DV-in feature. Luckily I didn't trash this cable so I was able to reuse the connector.

So, preparing the cable is really the easy part and all the needed informations may be found in the great guide from LightBulb that i mentioned above. It's just about soldering 4 wires on 4 resistors!

The part that is more difficult to do is to prepare the WRT54g mainboard to accept this JTAG connection.

You can follow two paths: you can just solder the JTAG cable on the mainboard itself or you can solder a connector on the mainboard
and then use a connector as well on the JTAG cable so it will be more easy to unplug it and.....to plug it back in case you need it again in the future!

Of course I followed the second option. So, the first step was to unsolder the pin hole on the mainboard to make room for the pin connector.

There is just one tool that is absolutely essential for this task: it is the unsoldering pump.

I used it quite a lot to suck out all the tin that is normally filling the holes where I should solder the JTAG connector. I have to be honest saying that it took quite a lot because I needed to warm as much as possible the tin in the hole, from both sides of the mainboard, in order to suck it out completely. On the other hand I could not stay too much time on the mainboard with the soldering iron otherwise I risked to burn out some component. So I had to wait a little bit beetween each pin hole "evacuation" in order to let the the board cool down.

After three-four shots per hole of unsoldering pump I voided all holes and I was able to solder in two 5 pins strips of contacts. Then I soldered a female connector on the other end of the JTAG cable and voilà, the cable was done.

Few minutes after I was dealing with software to understand what was wrong with my router and how I could fix it.

As all the guides are suggesting I quickly erased the NVRAM thinking that there was something wrong with it that was preventing the router from booting. I later discovered that I was right but the router didn't went on soon.

This was because there was not only bad data in the NVRAM, there was also a corrupted kernel image in the flash!

So, basically, after clearing the NVRAM, I had to solder another pair of pin strips in the holes on the right of the JTAG interface in order to connect to the serial port of the WRT. Of course I used the RS232-to-TTL serial interface converter that I made for hacking my MRT StorLink NAS. What a luck, I was really happy of finding already on my desk the right circuit that I needed! :o)

I used the serial interface to connect to the CFE bootloader in order to instruct it to load a new kernel and system image from the TFTP server on my laptop and save those image in the flash.

So, at the end of the game, I was able to fix the WRT54g in less than 3 hours, including the time needed to build the cables and interfaces, definitvely a good price for a brand new router!

Thank you for reading and........thanks to Lidia for the router! :o)

NAS Hack: OpenWRT on the MRT StorLink NAS (serial interface converter)

2008-04-07T19:56:10Z

As you saw in my last post, I was not happy at all of the firmware that my new NAS came with.

After playing with it for just one hour, I decided to see which chip it was based on and what was around in terms of hacks and (hopefully) improvements. As I was saying some days ago, I was really happy and excited to find that there's a great guy, LordScaffard, that completed the first porting of OpenWrt for this NAS!

So, of course, I was immediately looking at how to flash my NAS with that OpenWrt flavour. The bad news was that I needed to build an interface. This is because the standard RS-232 interface, which is the common serial interface that there's on the PC, works with logical signal of +12 Volts and -12 Volts that are too high for the serial interface that is on the NAS which is a TTL one. This one is working a + 3,3 Volts signal, so there's the need to use a logical signal converter that may adapt the RS-232 to the right voltage used in the NAS.

I managed to avoid to build such interface last year, when I was working on the Fonera. At that time, I was coding something in OpenWRT and I was flashing quite everyday my Fonera. So I bought the components needed for the serial adapter but I never built it. I was lucky and I flashed sucessfully the Fonera via software, so I didn't needed the serial interface.

So, at least this time I was able to decide to hack the NAS and to hack it really without going out to the electronics shop to buy the components! :o)
Anyway, it requires really few components: 5 capacitors and an integrated circuit!

So, after writing last post, I immediately started to build up my serial interface converter!
I used this electric schematics but I strongly recommand anyone that would like to try to build it to visit also this great page that shows by photo how to setup the converter on a prototyping board. Basically the circuit is using a MAX232 chip which is an integrated circuit that holds all the components to build the converter itself. It needs just some external capacitors to raise up the voltage from the +3,3 Volts to the +12 Volts.

You probably will find so many schematics in the Internet for this converter, and most probably you'll find it with different capacitors values. Basically there are several version of the original MAX232 and some of this version are capable to work with smaller condenser. In my case I used an equivalent chip, the ST232CN, with 5 electrolytic capacitors of 1 micro Farad each (and it worked out perfectly :o).

I followed the same suggestion that I gave you and soldered all the components on a prototyping board: easy and quick! Then I soldered also a DB-9 connector and a jumper connector that I got from an unused chip connector. The DB-9 connector is (of course) needed to connect to the PC's serial interface and the jumper connector is used to connect on the NAS board.

I plugged all together and......nothing worked out!!!
I checked and re-checked all the connections, I was really depressed because after two hours of work I didn't had any result, and, in addition, I didn't had the possibility to change the loosy firmware that was on the NAS!

After several minutes spend in carefully checking all the connections, I discovered that a bast...ehm a very mischievous pin of the chip was bent internally! It was the 16th pin, the Vcc! The pin that is powering up the chip itself! I unbent and inserted it properly with an extreme gentleness, I crossed the fingers and.....voilà!

OpenWRT is, of course, working ten times better than the original firmware. The porting by LordScaffard is not at 100%, it still lacks support for some functions and pheripherals. So (this will not sound strange for those who knows me) I immediately wrote him an email and............actually, even if I'm not a real programmer, I'm trying to give him an hand to adapt a more recent Linux kernel for the chip of the NAS!

LordScaffard is incredibly smart in kernel programming, and he's teaching me tons of things. On the other side, I'm trying to do my best, I'm learning really a lot and, of course, I'm enjoying a lot!

I really hope to see the kernel porting completion and, hopefully, to give an acceptable contribution to it. After that, it should be more easy to let all other OpenWRT packages work on this architecture!

Stay tuned!

A NAS (Network Attached Storage) for the Media Center

2008-04-04T13:00:10Z

Today arrived my new NAS!
I bought it on EBay, bidding from a German Ebayer that was really honest, precise and quick in the transaction.

I've choosen this particular one because it has 2 bays so it can hold up to 2 hard disks either Parallel ATA (PATA/IDE) or Serial ATA (SATA) and it has a 1 Gigabit Ethernet interface (instead of the common FastEthernet 10/100 Mbps). In addition there's an USB 1.1 port that can be used to attach to a printer in order to have the NAS acting also as a network printer server.

My first and quick test was with two old IDE hard disks of 6,5 and 40 GBytes. I just plugged them in and boot up the NAS to see what would happen.

To be really honest I was not happy of the product at the first test. I have a major problem regarding the network connectivity. The logical link is continuously flapping and I am able to operate on its HTTP interface only from time to time. From the network disk access point of view I have to wait when the NAS is reachable (when the logical link is up) and then access files, during copies or file moves the logical link is stable. So I had to launch big copies in order to work on the interface and look into menus and functions.

I think that this problem is coming from the fact that the switch that I'm using is a 10/100 Mbps and the NAS network driver is not enough able to handle the speed autosensing. Unfortunately there's no way to configure a fixed interface speed on it so I can't correct this problem for now.

So, basically it may be a good product but actually it has a crappy firmware and it is already the latest version!
So I immediately made some searches regarding it's chipset to find more informations and, hopefully solutions for the firmware.

I found that it the unit is a 35-HD-DUAL-NAS-E manufactured by MRT Communication. It is based on a well known StorLink chipset, the SL3516E from the Gemini family based on ARM processor. This means that probably there is a porting of some linux flavour to this platform.

Infact, some web searches after I discovered that there's an entire NAS-Central section regarding this unit. It is the MRT section where there's already available a porting of TinkyLS firmware and, wow, a very old friend: OpenWRT!

Great!
I think that next step will be to replace the original firmware with a more familiar one, and, hopefully compile by myself my favourite flavour of OpenWRT patckages! Unfortunately the actual firmware may be replaced just by using an interface to connect on the internal serial interface. So, the real next step will be to build up this serial interface!

Stay tuned!

DIY: how to setup a Media Center

2008-03-30T18:02:49Z

Around the TV there are normally a number of external devices like a DVD player, a cassette VCR a Dolby amplifier with the speakers. But there are also a number of different media like VHS cassette, DVD discs.
In the same place which, in my case, is the living room there's also a stereo player and a number of audio CDs.
In addition, when I want to watch a video from the computer I have to burn a CD and play it on the DVD player, even worse, when I want to watch a video from the Internet I have to move to the PC place sadly leaving the sofa!

Four months ago, in November, I started to think that this was unacceptable: I had to find a solution for this!

So I decided to build up a PC for my living room that would replace all those devices and play all my media from the same sofa ...ehm..from the same interface: the TV!

So, today I'll talk a little bit about what I did in the last months for this new project.

First of all I had to find a suitable PC. After tons of searches I was convinced that one of the requirement was to reduce as much as possible the noise of the PC.

So I took into consideration some mini-ITX fanless systems but, lately I decided that they had not enough CPU power to fit my needs. Infact they are actually able to play a video stream but they need an HW engine to encode a video from, for example, the TV channels.

I decided that the barebone PC from Shuttle were good enough for my purposes: they are compact, fully equipped with good CPUs, they have 2 slots for expansions and, on top of all, the CPU fan is not on the CPU itself but there are 4 heat pipes that bring the heat to the back of the cabinet on a big fan. The size of the fan is to reduce the rpm that it needs to cool down the CPU reducing the overall noise of the PC itself.

So I got through Ebay a Shuttle PC with a Celeron 2.8 MhZ processor for about €170 euro. The problem was that the one that I got through the only successfully bid was without video out connector... no problem, I had another video card with a good video out. The base platform was done!

The second step was to get a TV tuner card. After some other searches, I choose the Hauppauge WinTV HVR-3000 that is a combo card able to receive analog TV, digital terrestrial TV (DVB-T), satellite (DVB-S) and FM radio and have also a video-in: in just one slot I could have all the signals I wanted! Wow!

So I put up all together and......and started struggling to find the right MediaCenter software!

I have to confess that this was the most tricky and annoying part because none of the solutions I tried was fully satisfying my requirements.

My first choice was LinuxMCE 0704, because, of course I thought that for something that has to work like an "appliance" there's nothing better than Linux (to be really honest I think like this also for other purposes). I was really interested in it because it has tons of functionalities including the "follow me", the remote control distributed as application for smartphones and the possibility to do home automation through X10 controlled devices, wow!

Unfortunately I discovered that my TV tuner card was not fully supported under Linux, so I had to switch to a Micro$oft based MCE. In addition I didn't like the way LinuxMCE is structured because it looks like a "collage" of too many different software. The TV part is done by MythTV and I didn't like also the switching beetween the LinuxMCE standard interface and the MythTV interface. Last but not least I tried a lot of different video card configuration (in order to have the best tv-out signal) and, each time I made changes it took 10 minutes to re-render all the GUI.

Second try was the (yes I confess I tried it!) Microsoft Windows XP Mediacenter Edition 2005 and, just from the name length, you can understand how big, long, fat and heavy it could be. There is no easy or decent way to extend its functionalities and, in addition, it is so stupid that can't access a video on a network share unless it is mounted by the user "system", the only way to accomplish this was to schedule a batch script for the network share mount. Definitively useless (at least for my purposes :o).

Finally, I discovered MediaPortal! It is opensource, it is fast, well working and looking, it was supporting quite all the functions that I wanted and, for those features that were missing, there's a good community of users developing new plugins with new functionalities, wow! You can see a screenshot of how it looks like today in the head of this post.

There was just one function that I wanted but it was not supported, or, to be precise, I was not able to find at the first time the right plugin. The function was the integration with Skype.

So, also because I wanted to see how I could expand it, I started to code the MySkype plugin! (you can find it also at this link) I had to confess that it was the first time that I used the C# and I found it very funny! It is a very easy and fast way to code up application with very few lines of code. I enjoyed so much that I was able to go from the absolute MediaPortal and C# ignorance to the completion of the plugin in just a week! Yes, it was the Christmas week so I had some days off from work :o)

Lately I discovered that there was also another great Skype plugin from TesterBoy, Skype4MP. Infact I was contacted by its author that rightly asked me why I felt the need to create another Skype plugin. Unfortunately, at the time I started to code, the good version of the Skype4MP plugin was "hidden" in the forum messages, there was just an old and bad version of this plugin on the MediaPortal website, so I thought that it was more easy to start a new one than to understand a non-working one.

Now, I can say that I'm quite satisfied with my MediaCenter powered by MediaPortal. Basically I'm waiting two major enhancements. The firs one is the release of video functionalities in the Skype API, because actually it is not possible to extract the video from Skype by the APIs so the MediaCenter plugin is able to place voice only calls. The second enhancement will be the release of MediaPortal II which has a definitively great looking interface!

As you can see from the picture, I still have the VCR and DVD player in place. Basically I still need the DVD player to amplify the 5+1 signal from the MediaCenter to the speaker and I still need to add a big hard disk where to save all the content that I still have on the VHS, CDs and DVDs. I think it will take time for me to find a way to amplify the Dolby signal but surely I'll go faster for the second issue: I already ordered a big NAS where to store all my media! This will be the topic of one of the next post!

Stay tuned!

DIY: how to build a robotic arm gripper

2008-03-27T19:33:41Z

Today I will talk about how I finally (after about 2 years of delay) built the gripper for my robotic arm!

I know that probably the construction of just the gripper of a robot may be useless for everybody but, the method I used to build up the gripper may be really useful to build up the entire robotic arm itself.

Basically I kept the same approach that I used to build the arm, so I used the same PVC material, servos and screws. As result, unfortunately, the arm is actually a little bit heavy and the servos are really under their maximum load so that the two servo at the shoulder can't raise up the arm if it is in extension.
I think that I'll go over this issue installing more powerful servos. The one that I'm using actually are standard 3 Kg/cm torque servos, so I should have great advantages replacing them with 15 Kg/cm ones.

But.....stop chatting and let's see how I did it! :o)

First of all I prepared the base material, the PVC.
I got it from standard sewer pipes, of course new pipes and not used one!

I got some spare pieces of them for free in a construction site but if you can't find any you will surely find them in brico shops. The one I used is about 2-3 mm thick, you will also easily find the grey ones that are thinner (about 1 mm) but they can be used just for few parts of the gripper (the three layer structure) as it is too weak and probably will bend if used for other parts like the finger and the gears.

I cut a small piece of the pipe and then cut it on one side, the I placed it in the home owen! Yes, the one that resides in your kitchen!

After about 10 minutes at about 100 degrees Celsius (but it is bettere to make some test before as probably it will change from different pipes and owens) the PVC was so soft that I was able to get it out an press it beetween two flat wooden boards. This way I got free plastic board ;-)

The second step was drawing the gripper itself. The most annoying part of work like this is to copy the drawing on the PVC board in order to cut it.

I easily solved printing the pieces drawing with a laser printer and then using the toner properties to transfer it on the PVC board.

I mean that I simply placed the drawing on the PVC board, with the printed side facing the PVC itself, I firmly blocked the paper sheet with some adhesive tape then I ironed it at the higher temperature and.....voilà! The toner melted transfering to the PVC!

If you don't have a laser printer don't worry! It will work also if you print it out with an ink-jet or whathever other technology and then make a photocopy of it! So, if you would like to try it follow this link to download the gripper scheme that I used.

The third step, probably the longest one, was to drill and cut the PVC board. I used one of the most useful tool that I ever had: the dremel with the cutting disc! I

f you will try this please consider that it will make a lot of dust, PVC powder during the cut, so protect your eyes with pool glasses and your mouth and nose with a good breathing mask.

Last step was round down all the pieces in order to have them as precise as possible with a special attention for the gears. This part infact is the most difficult one and I proceeded in very small steps in cutting them.

There's one detail that probably needs some attention: when you transfer the drawing on the PVC board the heat of the iron will probably warp the board. I had this problem on one side of the board itself, and I simply ignored it and cut the PVC anyway, lately I placed the warped pieces on the iron and powered it up again. Then I took the soften pieces and flattened them like I did with the original pipe in the owen. I thought this way was more easy than try to flatten again the whole PVC board instead.

So, after some hours of work (half of a day more or less) I finally assembled my robotic arm gripper!

I have to confess, I'm already thinking about improvement to this version of the robotic arm! ;-)
But this may be the topic of other posts.....stay tuned!

Thanks for reading,
enjoy!

A robotic arm gripper, a mediacenter and a Wii finger tracker are coming!

2008-03-19T21:32:35Z

Ok, I have to really say sorry for all the time that I let this blog to be so silent.

The main reason is that I was so busy with work that I can't find time to writing posts, ok, at this moment I'm still busy at work but, to be honest, all this time I wast still thinking "damn, I have to go on with my blog!".

So, today, probably because I'm alone at home with no special things to do that I thought it was the right moment to start again posting my experiments and activities!

Infact, the biggest sorry that I have say is regarding the fact that last months I was not just working without experimenting something new! Not at all of course!
Since my last post I was giving up a little bit with the multitouch but I started (and completed) some new adventures:

I built a mediacenter for my living room with the great software MediaPortal
I coded a Skype plugin for the MediaPortal system
I experimented all the great Johnny Chung Lee ideas with the Wii Remote and I built an IR illuminator for one of them
I turned into a furniture maker and I build a bottle holder for my kitchen, ok probably this is not appropriate for this blog :o)
I finally built the gripper for my robotic arm!

Luckily I took photos and notes of all those works so, let's say that I have enough material to write down some posts full of hints for anyone that would like to play with those things.

Here is a small preview of what will be the next post on this blog!

So, stay tuned, BlaXwan is back!
:o)

Homemade Multitouch Display: mini guide first release

2007-11-13T22:25:46Z

..:.:: Click here to go to the guide ::.:..

In the last month I was very busy with my work so I didn't find enough spare time to dedicate to my multitouch. That's why I didn't posted anything, because there were no news to post about.

In this week finally I arranged to find a little bit of time at evening so, paragraph after paragraph I completed what I can say the "alpha" version of my multitouch display DIY guide!

Compared to the "work in progress" version that hopefully you saw after my last post, I completed the section two and basically wrote down from scratch the section three where I describe the construction of the FTIR multitouch itself.

As usual, I hope that it may be useful to you to face all the issues and doubt you can find along this building path and, why not, I hope that it gives all the common informations that probably were still missing in this site and that some of you were asking me in the comments or by email.

As I was saying in the last post, this guide is not intended as the ultimate reference for the construction of those kind of device. Honestly it is aiming to be at least a complete walkthrough for those who want to understand what a multitouch display is and how an FTIR one may be built at home, with very common materials and tools.

Please feel free to comment this post or the guide page to point out parts that are lacking informations or that are not so understandable so I can improve the guide and, hopefully, your experience in reading it.

..:.:: Click here to go to the guide ::.:..

Homemade Multitouch Display: a mini guide is coming

2007-10-18T21:25:41Z

I know that my Multitouch Display page has been left alone since I wrote it, with no updates even while I was anyway going on with my multitouch work and tests. In addition, when I write something on the multitouch matter, I'm assuming that everybody knows a lot of things, quite all I've learnt on it until now and I know that is not so useful. On the other side some of you rightly wrote me saying "why you don't give further and detailed informations on the construction, the components used etc.?".

I know that there are already tons of informations on the internet on this subject and there are some very good information depots as well. One of the best is the NUI Group wiki and, of course, the blogs of his users (thanks to DzHiBaS that aggregated them). But, in my opinion, there is still the need for something that may be a more or less complete walkthrough in the theory and the construction of those displays, like it is the how-to guide by Gravano that, unfortunately, was not updated lately with all the great improvements he made.

For all those reasons early this week I started to update the Multitouch Display page...and not only! While writing I reealized all those reasond and I decided to try to explain more clearly and starting from the beginning the whole story, aiming to reach the goal to put up together a quite comprehensive homemade multitouch guide.

Obviously this is not aiming to be "the ultimate guide" because I played just with FTIR setup and, in addition, my experience is limited just to my project and to the solutions and materials I used. But, anyway, I tried to put together all I know, I experienced and I read on this subject so I can surely say that, hopefully, this will be the best I can do.

Of course this is still a work in progress: there are already three pages to look at but there are some sections that still need to be written. Anyway, I really hope that at least anybody who is approaching for the first time this fabulous world may enjoy it and find it useful for its multitouch work.

I'll really appreciate any comments and suggestions you would post to enrich this guide and, why not, to correct any mistake in it. It could be a good tools for everybody or at least a good starting point.

Multitouch display, build your own: new compliant surface complete test

2007-10-11T21:40:18Z

Some days ago I was finally able to make a complete test of my new compliant surface made of the silicone rubber layer and the sketch paper. As usual, I can say that this was also a partial success.

The layers of silicone and paper gave great sensibility to my FTIR multitouch setup. Actually a very light touch is enough to trigger the blob recogniction, even the passage of a paper tape roll is detected!

As I was saying, there are anyway something to work on. The silicone rubber is still a little bit sticky and this cause the sketch paper to adhere to it for a little time after the finger touch passage. The result is a visible tray left after the finger movement. The software I used until now, Touchlib from NUI Group, is recognizing those trays as finger touches as well so that moving a finger result to several touches moving in a tray.

This bad effect is not impacting on simple application like Smoke but, unfortunately, it hardly impact on applications like the one used to play with photos. With this app, moving a photo result in enlarging it because of the multiple touches detected in the tray of the real finger touch. Anyway, you'll have a better idea looking at the video I shooted during the last test:

Actually, to be honest, I don't have big ideas on how to overcome this issue. I'm quite convinced that all those problems are coming from the type of silicone rubber I used, the Prochima Crystal Rubber, that is a good silicone rubber but probably not for this kind of (strange) applications. The other guys from NUI Group had infact better results with the silicone rubber layer without this kind of issues. My only workaround, for now, will be to buy and try other kind of papers and, probably later on, to try a different kind of silicone rubber itself.

But, anyway, actually I'm moving my interests also on software for multitouch. What I saw until now is that there's a lot of pieces around, most of them built using libraries or scriptable frameworks, few of them are compiled, mostly commercial and closed source. Unfortunately it seems to me that it is a lot of work done but in a fragmented way: there is no coordination and every app is a monolithic, separate app so that you cannot have a "multitouch system" but rather some multitouch-capable applications launched on a computer.

Actually I'm thinking about how to approach this matter, also because hopefully sometime in the near future I'll have a good multitouch screen and I will like to use it without the need for a mouse, keyboard or other "old" computer equipment.

In this brainstorming phase, every comment and suggestion is really welcome, feel free to contact me also privately.

Multitouch display, build your own: preparing a silicone rubber layer, video howto!

2007-09-30T09:47:41Z

When I tested for the first time my homemade multitouch display setup, I was too excited at the beginning to complain about the lack of sensibility. I had to press hard on the rear projection film to let the webcam detects the "blobs" of the infrared light bounced out of the acrylic. Later I understood this and I decided that it was the time to get a compliant surface made of silicone rubber as I was reading on the NUI Group forums.

I had a lot of doubts regarding the preparation because, of course, I never used this kind of material so I didn't had a clue of how to work with it. But the need was so strong so I decided to try at least once. Half a Kg of silicone rubber costed me 40 euro so I decided that this was my maximum budget to give a chance. But of course I didn't want to waste it!

Anyway, at the end of the game, I have to say that it was far more simple than I was expecting. I have to say also that I spent some time thinking about all aspects of the preparation process in order to avoid to waste the only chance I had for stupid mistakes.

I had great results regarding the silicone rubber layer even if later I had the surprise that, in my case, this layer alone with the rear projection surface won't work: I had to add an additional layer made of sketch paper to have the great sensibility that I was looking for.

I intentionally filmed all the preparation process thinking to make a video that may be helpful to someone else that is in the same situation I was, so, now that I saw the good effects of the silicone layer and after some (too many) hours of video editing, I can finally say:
HABEMUS VIDEO!

I really hope that you enjoy the video and that it may solve out any doubts you may have about the preparation of the silicone layer. Feel free to comment this post to ask for additional aspects or questions that I forgot to mention in the video or in the past posts. I would like also to know if you're going to prepare such compliant surface and, if you already did it, if it is working out for you even without the additional sketch paper layer.
Enjoy!