brainwagon

Okay, this is no big deal: lots of people have done it before. But while I was watching TV, I soldered some header pins to the DS1307 based real time clock board I got from sparkfun.com , and coded up this simple program to read the time from it. I’d never really used the Wire […]

A while ago, I remember hearing that DorkbotPDX had some deal where you could submit PCB designs and have them ganged with other designs and manufactured for a pittance (or at least, a small number of pittances) but I hadn’t bothered to chase down the details. Recently, I’ve thought of making a small board with […]

To control my simple Beacon, I used PWM and as simple (but slow) RC filter. That worked good enough for a test, but I really wanted the voltage changes to be more rapid. What alternatives are there? Well, I actually ordered a $5 I2C DAC board from Sparkfun, but it hasn’t arrived. The obvious low-tech […]

Analog Devices Microchip has this nice little application note on using pulse width modulation. Seems like it will be useful if you wanted to (for instance) generate some simple sounds using the Arduino. AN538: Using PWM to Generate Analog Output.

Some idle musings by hacker Jeri Ellsworth has spawned a contest for designs using the 555 timer. It’s not really my area of expertise (and designs are due by March 1, which doesn’t mesh with my current priorities) but if you have some good 555 ideas, check it out: 555 Contest: Welcome!.

A few days ago, I created a small program to compute bandpass filters using the equations from Experimental Methods in RF Design. Basically, you can pick a given inductor value, and then it solves for all the necessary capacitors. What wasn’t immediately obvious from the equations and the values that are generated was how these […]

The chaps over at the Batsocks blog sell a cute little gadget called the “Tellymate”: a nice little serial->video converter that is very, very simple. It uses a single Atmel AVR Mega, and handful of other extra components to implement a full character mapped 38×25 character display terminal which reads characters from a serial input […]

Okay, simulating the analog parts of the actual physical ring oscillator last night made me ask some questions, so I thought it might be useful to try a very simple discrete simulation. If you looked at the schematic I posted yesterday, you’ll note that the ring is really just made up of single transistor inverters. […]

Crap, the original entry I made for this got screwed up somehow. Oh well. Alan, VK2ZAY, was experimenting with ring oscillators, which make some very nice blinking light displays indeed. YouTube – Ring Oscillator Das Blinkenlights Before this post got mangled, I was experimenting with putting the circuit into LTSpice and analyzing it. My brain […]

I’ve been playing with a BASYS2 FPGA development kit from digilentinc.com, and pondering the world of digital system design. I chose the BASYS2 because of its low price ($70) and because it included a reasonable number of LEDs, switches, a VGA interface and a connector for a PS/2 keyboard. Still, I’ve been looking for other […]

I wanted some information on VGA signal timing. A few minutes of googling turned up this information. Bookmarked for future reference. VGA Signal Timing

A couple of weeks ago, I noticed a bunch of links to a 16 bit ALU designed to operate using blocks which are defined in the game Minecraft. It got me thinking, and ordered the book that inspired that work. It contains the specification for an ALU which is very simple, and yet surprisingly powerful […]

I’m intrigued by various uses for embedded processors, and so are my readers. I hadn’t seen this particular microcontroller board before, the “Teensy”, which is very similar to the Arduino, except that it is uses an ATMEL AVR chip with a direct support for USB. The link also points at a nifty interface to “soft […]

Anyone younger than me has probably never seen core memory, or even knows how it works. A very cool writeup, illuminating the actual workings of this technology from the past. One Bit Ferrite Core Memory – Wayne’s Tinkering Page.

32 bit processors now cost $1. That means that you can build fairly competent video games for the price of a coffee. Check it out: RBox: A diy 32 bit game console for the price of a latte – rossum’s posterous. Addendum: The prototype is actually built on a small board that can be ordered […]