Arduino (0022) problems coming from String and Serial libraries

When you start working with Arduino, you can find all the official libraries available at Arduino home page, the String and Serial are some of them.

In my last project (see my past posts Like Box or Boards are ready), I was using Arduino alpha version 0022. At the beginning everything was ok but when I started doing more complex stuff such as: concatenating strings, reusing string objects, assigning one string to another and overall leaving my app working for few hours…then serious memory leaks and corruption problems were happening. Programming with Arduino processing is particularly sensible to memory problems mainly because the loop() function is continuously running, so string objects are continuously being reused, resized, etc..

In order to have a more precise control of memory usage in my Arduino application I decided to use classic C language dynamic char arrays. For a programmer with extensive background in C language this was the shortest solution. Searching on google I realized I was not the only one having this problem so hopefully next Arduino releases fix this bug.

Another problem that I experienced while running my Arduino application is that the execution stopped at some point for no reason. After a while I realized that doing many Serial.println(..) was causing it, so I removed some and everything was working again. I suppose having a lot of debugging information going through the serial port could be interfering with the rest of operations.

Tips when using Arduino Libraries:

• Better do not use the String Library, implement dynamic char arrays instead.
• Limited Use of Serial.println(..).

And one last tip for debugging your Arduino Application: measure how much memory is free with the following code Free Memory!.

Like Box Project: Wrapping up!

There is no other better way than explaining the work through pictures! After finishing up the Like Box Project I want to show you the units from prototype to final version. In the next few days I will focus more on software and I will give some tips about programming with Arduino.
BTW, in this post I am using the “Awesome Flickr Gallery” plugin for WordPress, for now it works perfectly! It allows me to add a flickr set to any post even including description and title for each of the pictures.

Arduino Ethernet + Prototype Shiled

Arduino Ethernet + Matrix Led Displays

Arduino Ethernet + Matrix Led Displays

Like Box on Arquia Becas 2011

Like Box 10

Matrix Led Display 32x8 on Arquia Becas 2011

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Boards are ready to be boxed!

Finally, we have got our boards ready to be boxed!. Javi is working now on getting a customized clear plastic box for each unit. It’s gonna look fantastic!

Each unit consists of one Arduino Ethernet board, one Arduino Prototype Shield and two led displays of 8×32 pixels each. Since the units are connected to internet (we use a 3G modem router) the usage possibilities are enormous. In the picture we are showing on the displays the facebook like count of different webpages.

In order to get definitive connections we decided to get an Arduino Prototype Shield on top of each Arduino Ethernet, they are very useful and made our life much easier. In the next picture you can see definitive connections on the left and temporal connections on the right.

Temporal connections: for connecting the led displays to the Arduino we just use a breadboard (white plastic rectangle). Breadboards are useful during the testing stage when you still don´t know what are the final connections.

Definitive connections: once you know your connections you just need to solder the cables to the Arduino Prototype Shield (see left board). In our example we have soldered a flat 16-pin male connector to the Arduino Prototype Shield since this is the type of cable interfacing with the led displays.

It is piece of cake! any questions just leave a comment.

Could Facebook like and Tweet Buttons be used on physical installation?

These days, it is a must for each website to integrate a Facebook like and Tweet Button. These buttons are great for linking webpages with social networks, they provide an easy and straightforward way to share with your friends a web link and more.

Therefore, Are these buttons limited to be used in webpages? Can we use them on physical installations? are these technologies open?

Well, the answer is: it is possible to do that with Facebook like Button but not yet for Tweet Button.

I quote from Twitter documentation: “…in this early stage of the Tweet Button the count API is private.  As our systems scale we will look to make the count API public for developers to use…”

Meaning that, we still have to wait sometime until Twitter opens the Tweet Button so we will be able to use it in other applications beside integrating it within a webpage. I hope they have it done pretty soon!

surprisingly my web hosting is carbon neutral!

I found out by accident, I’ve never thought about that before, my web hosting is green! 

They are located in California and then I understood. I was in California two years ago and you could feel everywhere the obsession for being green… among other things like: eating organic, local and seasonal food, practicing yoga, and even following a strict vegan diet, in which animal products are eliminated.

As an example… it was impossible for us to find a place for eating meat in Santa Barbara…however we ate the most wonderful salad ever, fresh and juicy..

my first experiment with Arduino

I am entering Arduino’s world and… so far so good. The library for interfacing the led’s displays was available here, I would like to thank Gaurav Manek, his library it’s very powerful and well written, it saved me few days of work.

And now it’s about time for doing some more fancy stuff! keep you posted!

creativosencordoba.com behind the scenes

On Monday we (colaborativa) released our brand new Visualization at creativosencordoba. I am very excited since it is the first time I collaborate developing a website… you know I am more an iphone/C++/arduino/linux programmer.. It all started with a research on how to visualize data on the web in an intuitive, clear and useful way. We decided a treemap was the most suitable way for representing the creative scene of Cordoba.

After that, few days of watching video tutorials about javascript, jquery and d3.js, which is the javascript library for creating amazing visualizations. The result treemap is very interactive allowing us to select one or more categories and then take a look at the people in Cordoba that are working on those areas. The best thing is that people are collaborating including more creatives so the treemap’s shape is continuously changing and giving us new and useful pieces of information.

Looking forward to doing more web visualizations soon!

The unknown market of iPhone Apps

As I iPhone Developer many questions came to my mind when I first started writing apps. Searching on the web I wasn’t able to find information about the iPhone app market, specific information on how good independent developers were doing, if they were earning any money and so on.

One year later and with three iPhone apps on the market, I think I have finally found the answer to all my questions.. and I am gonna try to summarize few ideas in here. I hope it will help you on your iPhone experience!

Develop an iPhone app because you want to use a new media to present services/products, because you want to learn a new platform, because you want to have fun and lastly because if possible you want to earn some money. Looking at the following numbers at May 2011 (source http://en.wikipedia.org/wiki/App_Store) you can see who is really doing business: Apple by keeping 30% of our sales.

• 15 billion iPhone apps downloads
• 500,000 iPhone Apps approved by Apple (37% are free, average price 3.64$)
• 8,700$ Average Revenue per application
• 50,000 iOS developers
• 3,64$ Average Price per app

Of course we can find very successful iPhone apps on the App Store! there are some superstars iPhone Developers out there earning a lot of money, overall in games and utility apps. But according to few sources like this http://blog.creativethink.com/2009/06/lessons-learned.html: 90% of apps that go on sale in the App Store don’t even make back the money it cost to produce them.

There are a lot of independent developers who have always dreamt of working by themselves. Apple is given them an opportunity to do it with the App Store. Apple takes care of the commercialization side and independent developers put their creativity and efforts in iPhone apps. After more than 500,000 apps approved on the Store the competition is pretty hard and the chances of even getting back the invested money are low.

I hope you will use this info to make the most of your iPhone development adventure! Looking forward to see some changes in the smartphone world soon….

Good Luck!

Just keep on blogging!

Hi all, I know it’s been quite some time from my last post… what can I say?… I have been too busy and also I wasn’t feeling very motivated to be honest.
Looking at other’s people blogs I can see that blogging has to be part of my daily activities in order to be successful. But, When is a blog successful? well to me success is not measured by the number of people visiting a blog BUT by achieving a number of things such as organizing my thoughts, publishing information that might be useful for other people, sharing my open source projects, etc.
Wish me luck in my second attempt blogging!

here I go!

Select Annotation and Center MKMapView Around

When adding annotations to MKMapView it is nice to center the map around a particular selected annotation.
I have found many people on the net wishing to do that and having great difficulties. After struggling for a day I found a good solution to this problem: wait half a second after all the annotations have been added to the map before going ahead and select an annotation and center the map around.

This particular action has to be done at the end of the didAddAnnotationView function for having the desire effect.