Add the following:

sensors.requestTemperatures();

to the Part 2 code from the book:

TEM Image of Aerographite

Recently, I was shown this article regarding a new material being developed dubbed Aerographite. It seems to fall in the same category as aerogels where you create a network of carbon to develop a macroscale material that is very strong and very light. Aerographite is a network of woven carbon tubes that is being touted as the world’s lightest material.

What caught my eye wasn’t the specifications of the material, but the applications for it and the conclusions that people were jumping to. It reminded me of how a couple of years ago, Yi Cui developed his silicon nanotube battery anodes and everyone was claiming that devices would last 10 times longer when running on a battery. These articles, for the most part, seem to miss the fact that while these material advances seem huge on a lab scale specimen, they most likely have trouble scaling to production levels. The raw material specifications don’t take into account things like packaging when it comes to a full battery system, for example.

The aerographite article claims that the applications of this type of material are limitless and that it would revolutionize filtration systems and energy storage. The article made no mention how much of the material was produced and unfortunately I do not have access to the original paper to check this information. This is significant because of a similar material advancement in the last couple of decades. Carbon nanotubes (CNT) came into prominence in the 1990s and were seen as the solution for building a space elevator because of their tensile strength. However, CNTs ran into the issue of scalability for a project that size and we still don’t have a space elevator. It is very difficult to produce very long nanotubes and I see this aerographite as having a similar issue. While it is true that there are numerous applications, articles such as this one make it sound like those revolutions are just around the corner. 

What people must realize is that materials innovations take approximately 20 years to get from the lab to market. It is a very slow process and many of those “limitless” applications may never come to fruition. So the next time you read a similar article, appreciate the hard work the scientists have put in and the significance of the milestone, but please keep in mind that all the world’s problems are not solved and there is still a lot of work that needs to be done to get through the slow process of material innovation.

So one of the inspirations I had for restarting this blog was the fact that when I ran into an issue with following Michael McRoberts’ Beginning Arduino book, I couldn’t find a clear solution online. I decided that if I post my solution on this blog then hopefully some future reader of this book will be less confused than I was.

Overall, Beginning Arduino is a great book, but I disagree with the author’s claim that understanding the book requires absolutely zero experience. This may be true for the early chapters, but as the projects become more complex (and inherently more interesting), there is less explanation from the author about why certain things were done or how certain things work. This is an issue when things don’t work the way the book says they should and basic troubleshooting doesn’t find a clear solution.

I ran into this issue the most in Project 19 where I wasn’t sure if my approach was incorrect or if the author was doing something incorrect. I’m not the only one who ran into a similar issue so I will detail my approach below for when anybody else gets stuck on this project so they can have one more source of information.

Below are the components I used in my setup:

• 1x LED Dot Matrix Common Cathode
• 2x Breadboards (linked together to offer more working space)
• 1x Barebones Arduino
• 8x 100 Ω Resistors
• 2x 74HC595 Shift Registers

So for starters, I was using the Barebones Arduino and not the official Arduino Uno as used in the book. The first hurdle I reached was the book asked to use the 3.3V output of the Arduino instead of the standard 5V output. The Barebones Arduino does not have this output unfortunately so I decided to make a voltage divider using a 3.3 kΩ and 1.8 kΩ resistor (taking the voltage across the 3.3 kΩ resistor). This worked in the sense that the matrix lit up, but I ran into issues with flickering lights or some LEDs not turning on at all when a certain number of LEDs were already lit. This issue bothered me for the longest time until I decided to double-check the datasheet for the shift registers. What I found was that the shift registers were rated for anywhere from 2-6V, which was contrary to what the book said. The book mentioned that the shift registers operate at 3.3V, but it turns out they operate perfectly fine at 5V as well. So I removed the voltage divider, and voilà, the matrix was lit up properly as it now had the proper voltage for all the LEDs! I’m not sure why the author wanted to use 3.3V for the matrix, but this is the first big difference I found in this project.

The next major issues I found were in the code. The first thing I want to point out is that I used a common cathode LED matrix as opposed to the common anode matrix suggested by the book. This was mainly because I could only find common cathode matrices on Adafruit and didn’t want to spend time and money looking for a different site that had common anode matrices. Why is this important? The code in the book is written for common anodes and must be modified slightly to make it work for a common cathode (rows are cathodes, columns are anodes). This requires understanding how the dot matrix works to get the multiplexing working properly.

Pinout of Common Cathode LED Matrix (BL-M12A881UR-11)

In order to turn an LED on, the anode needs to be HIGH and the cathode needs to be LOW. So in the case of the common cathode matrix, the row needs to be LOW and the column needs to be HIGH for the LED at (row, column) to be on. I also switched around the resistors so they were connected to the columns instead of the rows so the conventional current would flow through the resistor first and then the LED. I don’t think this change is necessary but as part of my troubleshooting I did it as it made sense for consistency.

Even with these changes in mind, I could not get the code to work properly. This is when I found the Hands On Arduino blog and noticed the comment that the author made an error in the bit shifting part of the code. He bit shifted left when he should have bit shifted right. This change still didn’t get my matrix working. I ended up with either flickering lights or incorrect patterns showing. At this point I decided to just do the code from scratch and came up with the code below that did. I explain the code later on.

The beginning of the code is similar to the book where it includes the TimerOne library and initializes all the pins and the pattern to be displayed. The loop function just inverts the pattern every half second to provide the alternating animation. The real difference in the code lies in the screenUpdate function which is called every 10000 microseconds. First of all, instead of the shiftOut (or shiftIt depending on what project you’re looking at) function you write in an earlier project, I used the built-in shiftOut function that is a part of the Arduino library. I’m guessing the author has you write your own function earlier mainly because it’s a good way to learn how the shift register works, but the built-in one does the same thing and therefore has less of a chance of a coding error (especially since the one in the book changes between various projects). In this update function, first the pattern is shifted so it goes to the columns and then the byte value for the row is shifted to go to the proper row for multiplexing. This gets cycled through quickly in order to produce the basic animation of your pattern.

There is a key difference from the book code. The difference is that the LED pattern (led[k]) is not inverted while the row is (~row). This is the main difference in common cathode versus common anode. As you recall from above, the row needs to be LOW when the column is HIGH. The second shift register controls the columns, which is why the pattern is shifted first.

One thing that also doesn’t make sense to me, but works anyway, is that the for loop in the screenUpdate function iterates with a byte from 0 to 8. If you change the byte to int, it still works. But if you change the iteration to be from 0 to 7, which makes more sense to me since led[8] shouldn’t exist, it still works but the last row is very bright. If someone can explain to me why that is the case, it would be greatly appreciated.

Again, I hope this post helps anybody who may be stuck on this project by shedding a little more light on areas the book didn’t explain very well. Let me know in the comments if there are any other issues people may be having.

This past weekend, I had the pleasure of visiting Chicago and taking in its history, beauty, and humidity. I also got the chance to take in one of their best exports…comedy.

The Second City is a 50 year old improv and sketch comedy troupe that has been graduating some of the funniest minds in the country. Their list of alumni include the likes of Tina Fey, Stephen Colbert, and Steve Carell. It’s no surprise then that I was literally falling out of my seat laughing during the show.

“We’re All In This Together” is the 36th revue by The Second City e.t.c, which is the side stage troupe at the theatre. As the comedians even mention in the opening number of the show, it is what the audience chooses to go see when the main stage sells out (which seems to be quite often). However, the quality of these comedians are still top notch and I didn’t even realize there was a main stage until after it was mentioned in the show.

I came in expecting a pure improv show, but it turns out their shows are mostly scripted except for a few parts which are improvised. However, even the scripted portions are based in improv. Part of their process in developing a show is to improvise scenes and put what works into the actual show. This provides a higher quality production as it avoids many of the dead scenes that can occur in a pure improv show.

The layout of the theatre just adds to the ambience of being “in this room together”. It is a small black box theatre reminiscent of small college productions. There are small tables every few seats to give it a cabaret feel and waiters to get you drunk before the show starts.

It’s difficult to give a full review to a show that incorporates improv as some of the best moments will change from night to night. What I can say is that the comedians were skillful enough to make me question when some scenes were improv and when they were scripted. They hit all the right notes in keeping me laughing and there was only one scene that I considered dead (mostly because I didn’t get the reference). I highly recommend checking out The Second City if you are ever in Chicago as it is an affordable way to experience Chicago theatre and have a good time.

I would guess that the most common post on blogs is about the authors promising to post more and being diligent about it. Let this post be yet another one to throw into that statistic. The blog is still directionless, but I will throw out various articles and see where it leads me.

For starters, you’ll be seeing a post shortly (notice how I didn’t give myself a deadline ) about an Arduino project I recently did. I hope you’ll enjoy it!

So, the other day I ran across a very neat website that does something I’ve been wanting to do for many many years. How many of you have wanted to send a fax, but didn’t have a fax machine to send it with? Why would you have a fax machine? The technology is older than dinosaurs. Unfortunately, many companies and universities still require you to fax documents over and won’t accept anything over email. This is where FaxZero comes in.

Now some might say that eFax already provides this service and yes, it does. However, eFax requires a monthly subscription in order to use that service. FaxZero, on the other hand, is either free or pay-per-fax (via PayPal).

The way it works is that you can upload a document (.pdf, .doc, .docx, .rtf), enter in a destination phone number (international costs a little bit more), and send your document. You’ll receive an email confirming that you’re a legitimate user and by clicking the link in the email, the fax process will begin.

You can send your fax for free as long as your document is less than 3 pages long and you can send up to 2 free faxes a day. This fax will also sent with a cover page that has a big FaxZero logo on it, something they call as their “ad”. If you need to send more pages per document, you can pay $1.99 for the fax and the big logo will be removed or you can remove the cover page altogether.

If you’re wondering if this is legitimate, then there’s no need to worry. Not only is it BBB accredited, but I tried the free fax system myself and it worked like a charm. The quality is as good as regular fax quality and the cover page with the “ad” isn’t very obtrusive either.

The only issue I would say I have with it is that none of the pages that got faxed, including the cover page, mentioned how many pages were in the fax. This could be an issue with larger faxes and making sure the recipient gets everything.

So for all those who stumble across my site, let this be my quick post regarding this issue. It is NOT an issue. You may see the bars drop, sure, but that doesn’t affect your actual experience with the phone. If the bars indicator never existed, you never would have noticed a difference. So people, please stop worrying about these non-issues and causing events such as Apple’s stock dropping today for no reason.

Wow. Just wow. I have never seen a sporting event that ended like that. USA was tied with Algeria 0-0 while England was leading Slovenia 1-0. With the way the group stage works at the FIFA World Cup and the tiebreaker rules that are implemented, both USA and Algeria were going to be eliminated. But in one play, one second, Team USA was launched not only into the next round, but they ended up in 1st place among their group.

That is the first time since 1930, USA’s first ever World Cup, that USA won their group. It was also the latest goal ever scored in a World Cup match. For the third game in a row, USA proved that they never give up and they play for the full game. Another team I can think of should take a page from this book *cough*San Jose Sharks*cough*. This was truly a historic game for USA and what makes it even more historic is the level of engagement with this specific team and this specific World Cup.

ESPN has already had record viewership for these USA games, but this game in particular also tipped the scales in terms of internet traffic. This game had the second most internet traffic in history with the first being the opening of this World Cup and the third (formerly second) being the 2008 Presidential Election. But that’s not all!

I decided that I wanted to buy a USA jersey or shirt before I leave for Europe in a couple of days where I plan to continue to watch USA soccer in a soccer-friendly environment. It’s too late to order anything online so I called up 4 local sports stores that I knew carried sports jerseys and shirts. I called Sports Fever at Valley Fair mall and the Stevens Creek, Valley Fair, and Blossom Hill Sports Authority locations. Sports Fever doesn’t carry anything World Cup related. Stevens Creek and Valley Fair were entirely sold out. Blossom Hill only had a couple of small jerseys left.

Never did I expect soccer jerseys to sell out in any U.S. store. This USA team seems to be strong enough to get a country that couldn’t care less for soccer to start caring. That’s pretty historic. In fact, maybe in the future, I wouldn’t have to go to Europe to enjoy a soccer-friendly environment.

(P.S. – For those of you wondering where the word soccer comes from? Well, football in other countries is officially known as Association Football. In the late 1800s England started abbreviating it to Assoc. Football and the slang for it became Soccer Football. Hence the word, soccer. It also explains why Australia and South Africa also call it soccer. Turns out the U.S. didn’t just make it up after all )

So, I need somebody to explain this to me, because I can’t figure it out. I must be missing something elemental. In basic supply and demand, when the quantity of a product decreases and the demand stays the same, the price of the product increases, correct?

BP’s oil fiasco began on April 20, 2010 and the latest estimate by the government is that the spill is spewing out 60,000 barrels of oil per day. It has now been 60 days since the explosion, which means approximately 3.6 million barrels of oil could have been lost due to this disaster. With an annual import of approximately 4.3 billion barrels of oil a year and domestic production of about 1.9 billion barrels, this 3.6 million barrels is only .05% of total U.S. oil consumption (assuming all that is produced and imported is consumed). The spill hasn’t been stopped yet so this number could go up.

This .05% is a small amount of the total so I would expect either no effect on the price of oil or a maybe a small effect. What confuses me is that in the above graph of the crude oil price over the past year, the price dropped significantly around the time of the crisis. Why would the price drop? Shouldn’t the price at least increase because of a loss in supply? What am I missing?

Well, I’m waiting now and as I’m waiting I got to see the “Delivered on June 24th” message change to “Ships by: July 2nd” and then change again to “Ships by: July 14th”. I’ve very surprised by these delays and the pathetic strength of the Apple and AT&T websites. Why am I surprised? Because both Apple and AT&T KNEW this phone was going bring in a massive volume of orders. It’s as if they’re releasing a popular product for the first time. Have they learned nothing from the iPad, iPhone 3GS, iPhone 3G, and original iPhone?

Apple never should have released their product at this time if their (and AT&T’s) servers could not handle the traffic. Let alone having a small supply of their product, which required delaying the product shipment twice.