OMG A NEW POST

Hey everyone! Very long time, no posts! This will hopefully be the beginning of a revival of my blog, since I will probably have more time after finishing high school and starting college. Where am I going? Michigan Tech! Yes, that place in Michigan that’s pretty much as far as you can go before you hit Canada and where summer is about a week long. As you can probably guess, I’m studying electrical engineering. I really like it there and have met some great people that share my obsession for electronics.

Updates. The quadcopter is not done :/. It probably won’t get done either. I was quite close to getting it flying, but it would just sit on the ground and spin in circles. I built another(!) LED cube, this time with blue LEDs. I made a nice set of circuit boards for driving it, with the circuit still copied from the Instructable I followed for the first one.

LED Cube Control Boards
LED Cube Control Boards

Running the test program to verify everything is good.

LED Cube Testing

A (not very good) picture of the cube running the main program.

LED Cube

Well that’s all I have at the moment. I’m working on a big LED installation for our dorm room next semester. All I’ll say right now is it involves ethernet, a teensy 3.1, and 12 meters of Adafruit Neopixel LED strip.

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74C922 Emulator

So, while I am waiting on parts to build my quadcopter, I am also working on building a 7400 series drum machine. That’s right, 7400 series drum machine. I wish I had designed this, but I am _very_ slowly building this: 7400 Drum Machine. Why the sudden interest in 7400 chips? My grandpa stopped by a couple days ago with some real goodies. An entire tackle-box PACKED with mostly 7400 chips. There are also some 4000 series and several LM566 VCOs, EPROMS, and various other chips. It turns out that I now have most of the chips needed to build that drum machine.

There are a couple snags, though. Matt (the creator) used a couple (nowadays) rare chips in the design. One of them is the 74C922 16-key encoder. Yes, you can still buy these from some places, but they go for about twenty bucks a pop. Ouch.

Since I’m not entering any contests, like Matt did, I figured I might cheat a little bit. The 74C922 is a pretty simple chip; all it does is scan a 4×4 switch matrix and output BCD – binary coded decimal. It stores the last key pressed and toggles a “data available” output when a valid entry is made. This sounds like the perfect task for an AVR with some custom code.

Thus the 74C922 Emulator was born. My goal is to create an *almost* drop in replacement using an ATTiny2313. It will not be perfect, because the ‘tiny is 20 pins and the 74C922 is 18, but one should easily be able to make an adapter to plug my chip in.

There will be some people who call this “dirty” or “uncool” because I reverted to a microcontroller to replace basic logic chips. Okay, get me a 74C922 for 5 bucks – shipped. It isn’t cheating when you have to use modern technology to replace things that are no longer available.

You can take a look at the code on github as I develop it. I just started before I typed up this post, so it is not even close to being done, but it is there anyway.

Quadcopter PCBs Here!

Good news: the PCBs for the tinyCopter came in a couple days ago! Thanks to Laen over at the DorkbotPDX PCB order service for the stellar-quality boards! Now I can get to work assembling and testing the boards.

tinyCopter PCBs

tinyCopter Control Board

nRF24LU1+ Breakout Board

Now that I’ve more time to plan this project, I am really leaning towards using an off-the-shelf transmitter and receiver. The nRF24LU1+ is a really great chip, but unfortunately there is little information on actually programming (flashing firmware, not writing code) and actually using it. It looks like I may have ordered the extra components is vain, but such is the nature of developing (relatively) new devices.

Check out my photostream for more pictures!

Digital PSU Update

If you are subscribed to me on YouTube (if you aren’t, why not?), you know that a little while ago I started work on a power supply project. It is based off of the one that Dave Jones of the EEVBlog is building. Mine is slightly different, but has the same major components.

After I wore out(!) the first set of rotary encoder with my constant testing of the firmware, the new encoders didn’t work anymore. I tried everything with my code. I tried countless examples on how to get rotary encoders working on an Arduino. I tried changing the interrupt type, the interrupt routine, and the constants that define my pin setup.

The project sat on my desk for a while, getting nowhere. Suddenly, I had the idea to look at the datasheet again for the encoders I was using (EN16-V22AF15 ‘s) to see if I had missed something while wiring them. Lo-and-behold, there was my problem! When I wired the new encoders, I had (wrongly) assumed that all encoders had a standard pinout, and wired them the same as the old ones. Once I switched things around, they started working!

Now I can get the code finished, so the rest of you can build your own as well!

New Website, New Projects

Well, this is new. Yes, this is a complete re-design and upgrade. My old site, which is hosted at Webs.com, is still live, and will be for a while. It has become too…uh…bad. It is slow and messy, and the editor sucks. I also want to venture into the kit business. Let’s be honest, not even I would buy something from a site that looked like that. I’ve already got some ideas for kits, and am really looking forward to offering them for sale. Some of them will not be for beginners, as they deal with generous amounts of surface-mount soldering. Some of them will be more simple, and will be able to be enjoyed by both beginners and the seasoned hobbyists.

Thanks, and I look forward to what this site has to bring.

~nathan / qwertyboy~