This Old Blog

Originally published October 22, 2006 As mentioned previously I found a lot of the Vex hardware on sale during the summer. One of the supplemental kits I picked up was for tracks. The track kit comes with bogies, drive wheels, linked treads, and hardware (screws and lock nuts) to build two sets of treads. The following photo shows a completed square bot frame with the treads on the sides in place of wheels. The directions are fine for placing the drive wheels and bogies, but the method for firmly attaching the drive wheels to the bulkhead and to the drive motors is only lightly covered. If you follow the directions the driver wheels (the sprocketed wheels at both ends of the tread) won't stay on. Instead you have to come up with better assemblies at both ends. The following image shows how I used three collars to hold space a drive motor as well as keep the drive shaft in place. Two of the three collars had their tightening screws removed; they weren't needed. Those co...

Originally published October 22, 2006 After watching the prices of Vex equipment drop to half price or less all during the summer months ($149 for the Vex Robotics Design System, for example), I picked up enough hardware to build 3 1/2 independent square bots. What was missing for a complete forth is another Vex controller and radio receiver. I'll have to go back to the Vex site and probably pay full price for the components, unless I break down and buy a forth Robotics Design System. But I did have three controllers, so I finally found the courage to take the cover off of one and see what's inside. The controller has a pair of 18F8250 micro-controllers . Considering what's on the board and what it does, I find it quite clean in its layout and design (at least in my humble opinion). Plenty of nifty things to hack!

Originally published April 18 2006 (This was originally published here in January 2006) Two years ago Steve Hassenplug created a two-wheeled self-balancing robot using the Lego Mindstorms Robotics Invention System 2 and a pair of special sensors manufactured by HiTechnic. It was the same Lego Mindstorms that I had purchased that previous Christmas. Unfortunately when I finally found out about Steve's work it was nearly a year later, and a key component of his Legway, the HiTechnic EPOD Sensor , was no longer being made. Jump forward to November 2005, and I find out that HiTechnic is again building and selling the sensors, so I immediately ordered two for myself. While waiting for the sensors to arrive, I started to look at the other bits needed to build the Legway. Two years is an eternity in computing. Key software and support systems had evolved since the original Legway was produced. Elements of the Legway that had changed and needed to be updated were: I used the Linux ...

Originally published April 18, 2006 Section 2 of the Vex Inventor's Guide shows how to build a sample motorized chassis they call squarebot. There's some additional mechanical tweaks that need to be made to squarebot in order to make him a little more rugged. First of all, you should add a collar to the outside of each of the four wheels. This keeps them from coming off while the squarebot is rolling around for extended periods. See the two photos below. The first is an overall view and the one beneath is a closeup of two of the wheels with the collars. Next, you need to add spacers to the inside of the chassis subassembly holding the gears, between the outside of each gear and the outer chassis rail. It is annoying to be driving along and then have squarebot stop because the gears have slipped along the axles and no longer engage. The following picture shows the added plastic spacers, looking up from the bottom of the squarebot. They are the black shiny pieces between...

Originally published Tuesday, April 18, 2006 Welcome. This is a spin-off from my other blog, blogbeebe . The idea came from my wife and kids, who suggested I create additional online diaries to better categorize my interests. This blog covers my interests in hobbyist robotics; the kind that mere mortals can afford. I have been a tinkerer in robotics since the early 80's. It was an offshoot in my interest in microprocessors and microcontrollers, such as the 6502 and 8048 . In this day and time I have the Lego Mindstorm's Robotic Invention Kit (and several add-ons of parts), several Vex Robotics kits, and all the odds and ends I've collected over the years. I've been investing in Vex since November of 2005 when I paid $300 for my first kit. I've been buying more this April because Radio Shack, the seller of Vex locally, have cut the price for just about everything in half. So now I've got sensors and rechargeable batteries and spare gears and wheels and trac...

You're looking at my latest digital gizmo, an ARM-based Stellaris LaunchPad development board . At the heart of the board is an LX ARM Cortex-M4 32-bit CPU running at a modest (by today's standards) 80MHz. It comes along with 256K of FLASH and 32KB of SRAM. It won't run Linux or Android or any other major operating system, but for writing executives, interrupt handlers and I/O manipulators in C or assembler down at the bare silicon, it has more than enough raw computational power. I started my professional life nearly 40 years ago by building embedded systems with the 8-bit MOS Technologies 6502 and Zilog Z80. In both those instances the embedded systems had a lot less RAM and EPROM and I was very glad to have them running at a then-blistering 1 to 4MHz. The  also comes along with a lot of hardware-based timers and very flexible I/O pins. It is, for an old hacker like me, something of a dream come true. And I got it all for free from an old friend who had in turn g...