Going Mega

The Arduino Mega 2560

After some soul-searching, I decided to upgrade the project to the Arduino Mega, shown here. It just arrived today. Surprisingly, it’s still very small (4″ x 2.1″), but has eight times more program memory, and eight times more RAM, which I think I’m going to need. It runs at the same clock frequency, 16 MHz. It’s got more I/O than I can ever use. But I’m tempted to try!

Chest buss built

I built the full-scale chest buss tonight. I still don’t have a solid plan for how I’m going to suspend this thing on my chest yet, but at least it’s operational. Here it is plugged into MiniMe for a test.

Time for a new scope

Nice scope for the money!

I’ve got an ancient BK Precision 2120B analog oscilloscope in my studio that I’ve had for years. It works, but it has ground drift when it gets warm, and…well, compared to modern digital scopes, it kinda blows. So I’ve decided to get an Atten ADS1102CAL digital scope to replace it. It’s cheap, does FFT, frequency counting, storage, computer communication, etc. Not bad.

Encoder working

Groovy navigation encoder

I got this groovy switch-encoder thing from Digi-Key. It has four directional switches, a mechanical quadrature encoder wheel, and a center select button. I’ll be using this to control my UI. I have the Arduino reliably listening to this thing using two interrupts sharing the same simple interrupt service routine.

Arm and leg harnesses complete

I’ve got the full-scale arm and harnesses complete, along with their elastic straps. I’ve become an expert at fabrication with elastic and anorak snaps! I also made a temporary spine that lets me attach the arms and legs to the Arduino, so I’ll be posting some pics with those harnesses lit up soon. They represent 18 of the 50 total LEDs in the outfit.

Strapped guns

Full-size arm harness and straps

I made all the straps for the full-size arm harness. Here’s what it looks like all attached. The harness will attach to the spine at my upper chest (not where the wire’s hanging down in the picture). Will build another set of leg straps, and perhaps a test mini-spine so I can try these out running off the Arduino.

Time to get strapped

Approximate alignment between harnesses

I built five straps when I built the first full-size leg harness prototype, but I haven’t built any more since – they’re pretty tedious to make, and I have to a lot of hammering to put in the anorak snaps. But there’s not much avoiding it now. I need to make the complicated chest subharness, and in order to do that I need to make measurements with the arm harness actually mounted on my body.

There are some spatial relationships between LEDs on different harnesses that I’ve planned, such as the ones shown here. Those LEDs are supposed to generally line up, and it will be much easier for me to actually achieve that kind of alignment if I can take the measurements on myself, instead of just in theory. I feel like a tailor now. :-S

The long…limbs…of MiniMe

I just built the full-size leg subharness. Here’s both the full-size arm and leg harnesses attached to MiniMe’s spine. Every day I’m more glad I built that miniature.

Improved display

After observing the rather abysmal performance of my LCD over I2C, I decided to give it a go with SPI, which I read was a lot faster. The good news is that it really is a lot faster, and I in fact demonstrate here acceptable interactive UI speeds for activities like scrolling through a list, which involves changing most of the memory on the display all at once. The bad news, of course, is that now I need five more wires going to wherever this display is going to live, which I hope will be my wrist or the back of my hand. Perhaps it’s better anyway that I’m not polluting my I2C buss with instructions for the display.

First shot at display

I’m now spending some mental cycles thinking hard about real-time control of anthrolume while I’m wearing it. I ordered a bunch of parts for control and display, and they’re starting to come in. Here’s my initial experiment with interfacing a 20-character by 4-line LCD display to the Arduino. I am hoping to have a display like this on my wrist or the top of my hand.