Embedded Man

I’ve always been fond of state machines.  I don’t know why but perhaps it has to do with the fact that they have a visual representation that makes it easy to understand the sequence of operations.  Granted, I’m talking about well thought out state machines.  I have seen people abuse the state chart tool to get spaghetti code from an ugly state diagram.

For programmable logic design they are great but I don’t get to use them that often in software.  Most of the software projects I work on are already designed by the time they get to my hands and I can’t make architecture changes.  Still, I like to read about them and one good article I found some time ago is here.

In it the author describes designing UML State Machines.  He starts out by describing some errors that were found in a simple Visual Basic calculator program.  Errors that could be prevented by using state machines instead of relying on the traditional method of using if statements.  Not that there’s anything bad about using if conditions but we’ve all seen nested code that was almost impossible to read because it was so convoluted.

So, yes, state machines have more overhead and they are probably not the solution to all problems but they make nice alternatives to lengthy, nested conditionals.  Food for thought.

So here it is, the last day of the decade and I’m nursing a cold.  What a way to go out.  Oh well, maybe it’s a sign that next year will be better.  I hope you all have a great and safe New Year celebration!  See you next year.  Keep coding!

If you can’t make it to a lecture on C++, these videos will at least help you get a feel for what you’re getting into.  Even though C was for many years the defacto language for embedded systems, C++ is commonly used so you should get intimate with it.

In embedded software design it is common to want to have the code footprint as small as possible.  Therefore, it is fairly common when using the GNU C++ compiler to use the -O2 option which includes the -O optimization flags plus a whole slew of others.  You would think that the best optimization is always what you want when compiling embedded systems code.  Not so, my young apprentice, at least that’s what I found out the hard way.

I was building some code using a compiler created for MIPS and I began getting a long list of messages from standard input that looked like this:

Warning: AT used after ".set noat" or macro used after ".set nomacro"

These were followed by a long list errors that looked like this:

Error: Branch out of range

Needless to say, I wasn’t sure what was going on.  Well after a little bit of research a senior developer pointed out that the code had been assembled in such a way that a jump was being attempted that was more than 32K instructions away, thus causing the error.  And how did we fix this problem?  By removing the -O2 option from the compilation command.

You wouldn’t normally run into these kinds of issues with modern compilers but it turns out we were forced to use an older compiler (3.3.1) with an older version of the standard C++ library (2.2.5).  So there you have it.  A small tip when using older compilers.

Last week I attended the TI Tech Days conference in Dallas and it was a stark reminder of the state of the economy.  Last year TI had two major conferences, the TI Developer Conference and the Advanced Technical Conference.  This year they bundled both into one and shortened it from 4 days to 2.  The venue was still a nice place but you could tell that corners were being cut where possible.  I happened to notice that many of the rooms we were in had a large power supply sitting on the floor as if the main 220 box had been pulled from the wall and they had no place to put but on the floor leaning agains the wall.  It’s hard to describe and I should have taken a picture to show just how odd it seemed.

In TI’s defense, they’ve had to make changes to stay afloat (who hasn’t) and they even had the CEO, Rich Templeton, give the keynote address.  Now I don’t know how many gozillian-dollar companies have their CEO speak to the troops but it sure made me feel special, no lie.  What’s amazing is that the guy is not that old, he couldn’t be more than 45 (at least that’s my guess).

While Mr. Templeton is a good speaker he couldn’t disguise the fact that there were much fewer attendees this year than last.  No surprise given the state of things but it’s kind of sad because large conferences are cool.  You get to meet people from all over and you get to see a lot of cool innovations.

Hopefully, next year will be better.  Keep coding!

You may have been wondering where I’ve been for the past few weeks.  Well, besides from working some insane hours, I’ve been trying to created programs for my iPhone using the open source toolchain.  Now I’m all about open source but I have to admit this is a lot harder than I anticipated.  I tried to use Linux but I couldn’t get the decrypting tools to work.  Ironically, I was able to get the dmg decrypting tools to work in Windows of all things so I went with Cygwin.  I was able to build the HelloWorld app which was way cool but I’m running into roadblocks getting the other examples to work.  Oh well.

Sounds like a bad tabloid headline but, according to this article, some mean people hacked the Virginia Prescription Monitoring Program and stole some patient and prescription data and are now demanding $10 M to return the data.  This story was picked up by the AP whom reported that the state of Virginia refuses to pay the ransom.

This is a disturbing story for two reasons:  1) you would think that with all the cool things you can do with technology, why would people still insist on doing bad things?, 2) will this become a trend?

I don’t know if you know this but kidnapping has become a common thing in countries like Mexico.  It’s become so common in fact that now it’s starting to take place in border towns–on the US side.  Someone is kidnapped on the state side and quickly whisked away to the Mexico side where the law is less likely to find them before the ransom can be paid.

So what does Mexico have to do with this story?  Well if one person can hold data for ransom, who’s to stop this from becoming more and more prevalent.  I guess the first thing we should take from this is the importance of security and backups.  The other thing is that crime is crime whether its physical or cybernetic and when a crime is committed we all lose.

This is an interesting article I found via Clive Maxfield (Engineer Extraordinaire) about programming skills that were once mandatory.  One interesting bit was Hungarian notation.  I use Camel Case but I still prefix pointers with a lower case “p” so I guess I’m still a little old school.  Punch cards are thankfully no more but I remember hearing other engineers talk about using them.  I remember taking a programming class where the instructor mentioned the “goto” statement and just simply saying “don’t use it!”  Can you think of any that are not on this list?  If so, just add them in a comment and we’ll keep out own list.