BlackBerry PlayBook – Side Loading Apps

… or,

How to install MIT AI2 Companion (AppInventor) on the PlayBook

I have a bunch of BlackBerry PlayBook tablet at home in our office so I decided to make use of them. I thought to have the Android AppInventor would be a good one.

This a short guide how to do that.

BlackBerry PlayBook

Installing BAR files directly from the computer to the tablet, a.k.a. sideloading, is done through an additional app.

The best app (so far) is the DDPB, the last version is 1.0.9 (12/03/2012)
Website: (no longer available)
User guide: (no longer available)

The app is available for download on other websites.
DOWNLOAD: DDPB – Load Android Apps on Playbook and Blackberry 10

There are also guides how to work with te app as well as other useful tips.
ARTICLE: Side Load PlayBook Apps (Windows)

NOTE: Installing the DDPB may cause issues – error asking for Microsoft .Net framework version 2.0 or compatible.

SOLUTION: DDPB asking for Microsoft .NET framework 2, already have 4 (Windows 8)

The original Android APK files should be converted into BlackBerry PlayBook BAR files.

TOOL: PlayBook .apk to .bar converter

Example, MIT AI2 Companion:

Simply download the BAR file and add it the DDPB, the press the “install” button.

Other Tools: localbar2



A tiny vibrating bot

Tiny vibrating robotThis weekend I had nothing to do so after watching that video on YouTube about the Kilobot project I decided to build something similar but much simpler myself.

It took me just couple of hours to make the mechanical part of it. For the “brain” I used one of my header broads based on Atmel AVR ATtiny25 chip.

It still needs improvements, especially the vibrating motors – right now it could turn left and right but has difficulties to go forward. I should probably change their angle or adjust the legs.

I shot a short video about building it with few seconds in the end with the robot crawling around.

Nice, isn’t it.



My ATtiny Tiny Header Board

This is a personal project to build a header board for the Atmel AVR chips of the ATtiny series and more specifically 25, 45 nd 85. It should be also compatible with the ATtiny13 chips.


I really like the ATtiny series, especially the 8-pin chips – they are small but provide enough resource to build simple stuff. They are cheap too.

Here are some of the goals for this project:

  • Easy to understand schematics – with the minimum required ATtiny external components, that’s really simple.
  • Simple to assemble board – just few components – no SMD.
  • Easy to find and cheap components – it is only the IC and few other components.
    I was able to buy everything from the local hobbyists store and from Internet at very attractive prices.

Schematics and Board

ATtiny Tiny Header Board Schematics

I designed the circuit at This site is great. It allows me to to draw the circuit and then, after I’m finished, I can design the PCB as well. It have some glitches and need some improvements but worked just fine for my simple project.

That was one of my first projects on this website and as it turns out later when I received the PCB’s I made some designing mistakes – like size of the pads.

Design Considerations

I chose 10-pin ISP connector because this is what I have at home but also because most of the ISP programmers on the market today, especially those available on eBay, are equipped with such connector.  I chose the one that is larger – with a shell.

I put 2 8-pin headers type 2×4 on each side of the IC. I did this for two reasons:

  • For simple stuff I can use it as a breadboard – there are the IC signals on one row and GND on the other.
  • For more complicated stuff I can always add a shield-like board on top of it.
    (later I figured one of the headers should be longer than the other so the shield won’t be put in the wrong direction)
ATtiny Tiny Header Board PCB

There is a RESET button.
(later I realized that this may not be needed in most case and it takes too much space on the board)

There are to jumpers on the board. I put them because in some of my projects I need to connect external power source and at the same time measure the current that the board draws from it.

There is no Xtal on the board nor space for it. I think this is not needed in most cases. Anyways, for more complicated projects it could be added to the shield board.

There are no built-in LED’s on the board, as I would put on most of my experimental boards, since they may not be needed in general. No need to waste space.

Ordering the PCB’s

ATtiny Tiny Header Board PCB
PCB’a Ready

I ordered the boards at For 3 PCB’s I paid $5.40 – that includes international shipping (to Bulgaria) – that’s $1.80 per board. Good price. The whole process took 21 days – from putting the order until I got it in my mailbox.

The process is very simple: I downloaded the zip file from the website (my project is at and uploaded it to directly without any modifications. It worked right away. The board is currently located at

The boards arrived yesterday – they look great.  They also have nice ENIG (gold-platin) on the pads.

Even before I started assembling the board I noticed some problems in the design.

  • Apparently  the footprint that I chose for some of  the components made them with tiny pads – will have issues soldering them. But those were already made components at and I couldn’t change them.
  • Another thing, not that important though, was that some of the white print (the text labels) were too small – this could be fixed very easy in the next version.
  • The holes for the tactile RESET switch were too small – it won’t fit for sure.


ATtiny Tiny Header Board Completed
The board completed

The holes for the tactile RESET switch were too small, so I soldered it on the surface. Similar problem with the ISP connector but somehow I managed to solder it.

Since this board will be used for prototyping it will be good to know what all those PIN’s are for, so I put stickers on the 2-row header connectors with names for the IC pins.

For more flexibility one of the power connectors is a jumper (2-pin male header) while the other is 2-pin female connector.

Planned Updates

There are few things that I consider changing in the next version of the board.

  • Remove the RESET button. It is not needed in most cases but if necessary it could be connected externally directly to the PIN1 of the IC or if it is part of the functionality of the project could be added to the shield board. Although, the pull-up resistor hooked to the PIN1 of the IC should remain.
  • Remove the power jumpers. They take too much space on that tiny board and will not be used that often. External power could be connected through the 2-row headers.
  • 2-row headers should be different in length so if there is a shield board it will not be put the wrong way. One 2×4 header (for IC PIN1-PIN4) and another one 2×5 (for IC PIN5-PIN8) sounds like a good choice – The extra length will not take that much space on the board but will make it a lot more universal.
  • Make pads larger. For some of the components, like the ISP connector they cannot be soldered.
  • Make the text labels (white print) larger so they could be easily read.
  • Use the simpler version of the on-board male ISP connector (no shell) so it will take less space on the PCB. Add also the necessary white print to tell how to put the female connector.
  • Add more text labels (white print) with components names, parameters, etc.

Current Status

This board works just fine, there are no errors in the schematics or on the PCB.

It needs some improvements in the design, but most of them are not critical.

Interlecta presentation went very well at Mobile Monday Sofia

Neven Boyanov, Interlecta - Mobile Monday SofiaInterlecta presentation at Mobile Monday in Sofia went very well. I had the chance to present the company, our business, what our goals are and how we’re going to achieve them. Quite few people told me that my lecture was the most interesting one from the three presented there.

Other interesting topics that were discussed were investments in our region and investments in start-up companies, that was presented by Oriens. The other lecture – how to start a new mobile operator was not very interesting, in my opinion.

Later, during the networking, we were able to talk with other people, to exchange ideas and share some experience and opinion. It was interesting.

The presentation was uploaded at this address Mobile Startup – slides 20100222 web.pdf as PDF file and at this address as web page.

Interlecta invited to Mobile Monday Sofia to tell their story

Last week I received a call from one of the organizers of Mobile Monday Sofia asking me if I could tell there the story of our company Interlecta. It was very nice to be recognized as one of the successful mobile startups.

Here is my brief agenda:

  • The idea. How we’ve got the idea of creating the product and starting a company.
  • Little history. How everything came together.
  • The team. Who we are and what takes to be part of a mobile start-up Interlecta.
  • The goals. What we’re trying to achieve and at what cost.
  • The approach. How do we enter the international markets and what makes a mobile start-up different from other companies.
  • Key business components. What are the most important relationships that a mobile start-up should establish.
  • Marketing. Non-standard and low budget approaches.
  • The learning. What we’ve learned along the road.
  • The future. What we expect from the future and how we adjust our business to the present economic environment.
  • Q&A.

Interlecta invited to Mobile Monday Sofia to tell their storyThe Mobile Monday Sofia event will take place on February 22, 2010 at “Matti” hall in NDK.

Event agenda

  • 18:30 – 19:00 Registration and networking
  • 19:00 – 19:05 Introduction
  • 19:05 – 19:20 Session 1: Viktor Dimitrov, Investment Manager, Oriens
  • 19:25 – 19:45 Session 2: Stanislav Georgiev, Head of Integrated Telecommunication Solutons, Mobiltel
  • 19:50 – 20:05 Session 3: Neven Boyanov, Co-founder and Managing Director, Interlecta
  • 20:10 – Open networking

More information is available here:

Short link to this page:

How to setup Try’n’Buy product at RIM/BlackBerry App World

Interlecta Translator at App WorldThis is based on my personal experience while resolving issues with the products of our company Interlecta, and it is not a general solution.

Start with a new product

It is always better to start with a new product. Don’t use previously created product that was free or paid – the time you could save by doing that will cause more troubles afterward.

This is mostly because the existing user that have already downloaded previous versions will have problem upgrading to the new release, either “try” or “buy” one.

Incremental versions

Cannot get the correct version. One of the first problems that usually occurs is that people cannot see the correct version depending on whether they have purchased the product or not. The issue present almost in all cases when someone downloaded the trial and then purchases the full version – the result is that they cannot download the full version because it is not available on the screen.

Interlecta Translator at App World

Cannot upgrade. Another case would be when there is an upgrade of the release. They see the message, a notification by App World, that there’s a new version but there’s no button to download it.

Always increment versions. What we have learned while trying to resolve those issues was that the versions should be always incremental, i.e. the “buy” versions should be greater that the “try” version. Example: our Interlecta Translator trial was 1.3.19 while the full version was 1.3.21. That makes sense from database design point of view, but it’s not convenient at all, and such behavior is not documented, you have to learn it from experiments.

Problems with upgrading to full version

This is a common problem.

Canno upgrade to new release. If you have new release of your Try’n’Buy product people will receive a notification but when they go to the product screen at App World they will not be able to do the upgrade simply because there is no button for doing that. In our particular case there’s only a button to install the trial version.

Interlecta Translator at App WorldAn experiment worth trying. What we’ve found out is not a solution, but is more like a work around, it’s annoyingly slow process, but it’s ate least something that may help your customers. In short, you have to: Remove your application from App World; Remove the App World itself; Reinstall the App World; Login to App World through PayPal; Reinstall your application. It also involves rebooting your BlackBerry 4 times. That’s not convenient at all, but was the only was for me to get the latest full version.


More details were posted on our company blog at

There’s also discussion at supportforums forums:

Please share your experience following the steps above, either here or on our company blog.

Haitian Creole available for Interlecta Translator (RIM/BlackBerry App World)

Haitian Creole for Interlecta Translator

Haitian Creole is now available for testing on Interlecta Translator for BlackBerry, downloadable at RIM’s App World application store.

Just couple of hours ago we have finished the first testing version of the new functionality of our BlackBerry application – Haitian Creole.

I have to admit that recently I’ve been talking with quite few people about our initiative to provide Haitian Creole, and especially Marian Douglas-Ungaro. We spent last several days looking for the best technologies to combine to bring that new feature to life, and finally today late in the afternoon we’ve managed to get the first translation on my BlackBerry from Engliush toHaitian Creole.

I don’t know how many people will download this and use it and how many of them will be doing anything in Haiti, but I’m glad that are able to provide that service. And not only that, we are the first company to offer that kind of software for BlackBerry.

The product, Interlecta Translator with Haitian Creole, is available for download at App World. There’s 7 days free to try download, but for some regions and countries it is available for free – just open App World on your BlackBerry and do a search for Interlecta to find out.


Interlecta promoted on App World

Interlecta Translator at RIM/BlackBerry App WorldThis morning our application for BlackBerry was promoted on the front page of the the RIM‘s App World and it will remain there for about a week.

There are some new features that we added since the last time it was there, most notably the connection diagnostic and setup tool. That allows the application on the first start to test all the available for the device connection and choose the best one, preferably the BIS-B because if its high availability. Of course it could be manually setup ti use Wi-Fi to save some bandwidth.

The application is priced at $2.99 and has a 7-day trial period, so you don’t really need to buy it before you see what you can do with it.

There are quite few new features coming up in the next version of the application, scheduled for sometimes next month, but most interesting will be probably our solution for the problem with missing fonts on your BlackBerry and the square boxes you may see sometime, especially when you receive Asian texts. I will post more info here and on Interlecta website when it becomes available.

Implementation of FNV hash in PHP

FNV is a simple algorithm and produces good results.

I needed this functionality as part of another project that required automated generation of relatively large number of unique usernames based on information provided by the user.

Some challenges:  Apparently PHP does not work well with numbers, especially large ones. I spent few hours trying to find out why my implementation was not producing correct results, … realized in the end that arithmetic with big numbers is something you should not do with PHP. To resolve these issues I had to use bitwise shift and add operations instead of multiply.

I put the code here:

… and a simple wiki page here:

More information about the Fowler-Noll-Vo hash function could be found here:

Lecture about Mozilla at the University of Veliko Turnovo

Thanks to the kind cooperation of Interlecta, a lecture about Mozilla in Veliko Turnovo is to become a fact.

Bogomil Shopov will talk about the history of developing the open source browser Firefox, since the first Mosaic through Netscape, Phoenix till its present version and the browser’s upcoming fifth birthday.

The second and more interesting discussion will be about open web as Mozilla’s vision on this subject is fundamental about the Internet freedom and sharing, the adequate usage of the web, and the right to own one’s personal information and contents in the world wide web.

Several of Mozilla’s products will be presented in the third part of the lecture and it will be outlined how everyone can contribute to their development.

According to the information published on Novinite website (a Bulgarian news release website) Mozilla in Bulgaria is more popular than in the rest of the world as a whole. In Bulgaria Firefox is used by 39.1% of users and by 23,75% in global plan.

In October last year Interlecta released the Firefox translation add-on MozTrans which gained popularity very quickly and is now used by thousands of users.

The lecture will be on Thursday, October 15th, in Corpus 3 of “ Cyril and Methodius” University of Veliko Turnovo, starting at 4:30 p.m.

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