Monday, September 21, 2009

Hardware, Software, and Firmware

Apologies if this post sounds like an advertisement for LEGO products...

To get set up for the LEGO Engineering program, the school bought the LEGO Education NXT kits - the standard 9797 set. We also bought a site license for the NXT Software 2.0, which (new in 2.0) includes "data logging" capabilities. That means that you can take measurements (using any of the sensors) over a period of time and record the data. You can then graph the data - either on the NXT or on a computer. I'm really looking forward to using these capabilities. Note that there's no difference in the NXT brick - it's just the software.

Firmware Version 1.28
With the NXT 2.0 software comes a firmware update, to version 1.26. But... don't install it. I heard from one of the attendees at our LEGO Engineering Conference that his NXT sometimes froze when doing line-following. The good news is that there's a firmware update (1.28) which he said fixed the problem. I highly recommend it. It has a very, very cool feature: you can do simple programming directly on the NXT brick - no computer required. I'll try to make a post about that feature.

Based on one person's experience, the 1.28 firmware seems to be compatible with the 1.0 NXT software - which is great! However, if you decide to try it, make sure that you have the older 1.05 firmware handy in case you need to revert - just in case.

One annoyance is that the firmware comes in a ".rar" file, an archive format like ".zip" or ".sit". I had never heard of it, which is saying something. On Windows, I'm told that WinZip, which you may already have, can unpack the file. If you don't have WinZip, the free utility 7-Zip will do it. On the Macintosh, a program called The Unarchiver will do the trick.

Charging Multiple NXT Bricks
I lied. The school didn't buy the standard 9797 kits. Those come with the rechargable battery (good) and a wall-wart style battery charger (bad). I hate wall warts. I especially hate the thought of 16 of them plugged into 5 or 6 power strips, plugged into another power strip. So, I had the school buy the W991501 8-Pack plus light sensor - you get a second light sensor and no battery charger.

So, how do we charge the batteries? Long ago, I started out as an electrical engineer and I still like to tinker. I built 3 "multi-chargers" that can each charge 5 NXT bricks. They take up way less space, have longer cords, and less wire tangling.


  1. I just edited this post to reflect a some new information - one of those transformers mentioned above is really only good to charge 5 NXT bricks. I'd thought that it could handle 6, but I was wrong, wrong, wrong. The transformer has a slow-blow fuse in it to protect things, but I managed to pop 3 of the fuses once our classes started to really drain down the NXTs. (You can, in theory, replace the fuses - Littlefuse #0230005.HXP - but you have to crack the transformer case open with a hammer and chisel, then glue it back together.)