brainwagon

The other day I mentioned that generating random Latin squares was a bit more complicated than I thought, and that an algorithm by Jacobson and Matthews was the way that people typically did it. I worked up this implementation based on a couple of different descriptions of the algorithm (the original paper was behind a […]

Lately, my lunch hours have been spent working on the NYT Crossword with my lunch companion Tom. While I find that the Thursday crosswords are often beyond my ability to do in the allotted time, between the two of us, more often than not we manage to plow through them. Slowly over time, we’ve begun […]

Backtracking is a better technique, obviously. The version from earlier today was actually not very clever, and took half an hour to find the 73,712 solutions to the 13×13 checkerboard. This version is less code (just 91 lines, compared to 107 for yesterdays) and finds all the 13×13 solutions in just 2.5 seconds (a speed […]

A question on Quora set me thinking about solving the N Queens problem, which is to list all ways that N queens can be positioned on an NxN checkerboard such that no queen can attack the other. I seemed to have misplaced my implementation of this that I did in Python, so I decided to […]

I was trying to figure out how to screencast to twitch.tv using ffmpeg. A couple of hours of tinkering resulted in the following command line which does a bunch of stuff. It captures the X desktop at 15 fps and 1920×1080 resolution. It grabs frames from my webcam (a Logitech Pro 9000) at 320×240 resolution. […]

Most of my hacking occurs in a vacuum: where I sit in my living room or in my home office and toil away silently on projects which occasionally get documented here, but which all too often are just my way of passing the time. On the way to work, I was asking myself what I […]

Okay, it’s been a long time since I wrote anything here. Not really a lot dramatic going on in life, I just have been spending my free time writing for Quora rather than my own blog. But I still am nerding out from time to time. Last night I dusted off an old project of […]

I hadn’t been flying my DJI Phantom 2 since last year (before I herniated two disks in my neck) but I’ve been meaning to take it out and get it in the the air. This week, two different things happened which provided some incentives to get it in the air, for reasons which weren’t entirely […]

A couple days ago, one of my Twitter or Facebook friends (sadly, I forgot who, comment if it was you, and I’ll give you credit) pointed out this awesome page: Reversing Sinclair’s amazing 1974 calculator hack – half the ROM of the HP-35 It documented an interesting calculator made by Sinclair in the 1970s. It […]

Ken Boak had mentioned on twitter that someone was creating a blinken-lights front end for the simh simulator of the PDP-8, called the PiDP-8, since you can power the entire thing from a Raspberry Pi. Very cool, but not quite available yet. What was available from Oscar is the Kim-Uno, a simulator for the old […]

A few weeks ago, I was scanning the Deal Extreme website, and ordered a few different LED displays, not because of any pressing need, but because I wanted to have some display options available if I needed some for a project. I was especially interested in cheap LED displays. One of the ones I ordered […]

Yesterday, I got a small 4 digit, 7 segment LED display board in the mail from dx.com. Cost was around $3 shipped, and the module uses a 4 pin interface (power, ground, clock and data). Originally, I thought it was I2C, but like other modules I have received based upon chipsets made by Titan Micro […]

Previously, I wrote about a project I called the Big Box O’ RF. I’ve shifted goals a bit, and done some experimentation, and have changed some of my goals and approach. First of all, I’ve changed the goal a bit. Instead of being a piece of test equipment, I’m actually more interested in using it […]

One of the things that I really like about the Teensy LC (besides its low price) is that it has three hardware serial ports. Hardware serial ports are just nicer than the SoftwareSerial ports that you see on the ordinary Arduino platform. While the latest support for SoftwareSerial ports on digital pins work reasonably well […]

I hooked up my new DS3231 clock module to an Arduino that was being fed with the one pulse per second input from a locked GPS, and counted the number of pulses from each. In 3170 seconds, the clock module generated 103874565 pulses, for an average pulse per second of 32768.0015773 pulses per second. That’s […]