标签: DigiRule

Much like Douglas Adams' fictional detective Dirk Gently, I'm a great believer in "the fundamental interconnectedness of all things" and how one thing so often leads to another.   Several days ago, for example, I received a bunch of emails requesting consideration for a free GPAK4 development board. The problem was that I'd written about it yonks ago.   So I asked one of the guys what had led him to that article, and he responded that he'd seen a reference to it on the DangerousPrototypes.com website. Well, this sounded like an intriguing destination, so I immediately bounced over there to take a look, and the first thing I saw was something called the DigiRule.     This little beauty was created by a guy called Brad. You can find out more about Brad and his creations at BradsProjects.com . In a nutshell, the DigiRule is a 6-inch (15 cm) ruler whose divisions are marked in binary rather than decimal.   On the rear of the ruler we find useful information like logic gate and flip flop truth tables, a binary conversion chart, a few select SMD component footprints, and some hole sizes. On the front -- as you can see in this video -- we find a bunch of buttons and LEDs and digital functions like primitive logic gates, different types of register elements, and a 4-bit binary up/down counter (all of these functions are actually implemented using one of Microchip Technology's PIC18F43K20 microcontrollers).   As I've said before on many occasions: "Show me a flashing LED and I'll show you a man drooling!" I want one. Brad isn’t selling them. I'm going to have to build my own. Even better, maybe I can persuade my chum Duane Benson to build some for us, because (a) he can whip out a new board design much faster than yours truly and (b) his designs usually work first time.   But if we're going to build our own, then you can bet we're going to add a few features of our own. For example, we could make the little rascal Arduino/chipKIT compatible and provide it with a USB port so folks can hack it if they wish (we'd make this an open source design, of course).   I do like the simple logic functions and registers on Brad's ruler, but -- in the case of the simple logic gates, for example -- he uses only one color of LED. Thus, in the case of the AND, function, the LED representing the output is only on (logic 1) if both of the inputs are on (logic 1). I'd prefer to use bi-colored LEDs, where green represents logic 0 and red represents logic 1, for example.   What else could we add? How about a real-time clock capability, possibly with a small OLED display to present the time? (I think we're going to need to use a rechargeable battery.) Maybe connection points for two flying lead probes and a piezoelectric sounder so we could use it as a continuity tester -- perhaps even a simple multimeter...   What say you? If you were going to do this, what would you include on the little scamp? Any suggestions will be gratefully received, but you'd better throw them into the mix quickly.