Outside

Inside

USB Connectors

Charging my iPad

Schematic

Closeup of foot

Battery and Connectors

Internal partition

The yellow piece is some scrap expanded PVC left over from a laptop desk I built for my wife a while back. The PCB is mounted to this, opposite the battery.

Partition & chamfer

The bottom of the partition is chamfered and held into place by another piece on the bottom. This lets it set into place easily, but still holds the battery in place tightly.

Specs:

• Box – $6 brand new at the local thrift store, I only added electronics and handles. (I need to head back and get a couple more!)
• Battery – 12V 7Ah (~12 iPod charges or 3.5 iPad charges)
• Output – 5V @ 1.5A (will charge iPad while watching video)
• Connectors – 3x USB Type-A female
• 3A fuse directly on battery
• Power switch with blue LED indicator

Plans for the future:

• “Working” steam power plant
• Microcontroller based monitor (Battery charge level, internal temp, etc) with 128×128 OLED screen
• Embedded wireless web server (WRT54G based)

I have been thinking about the PDA for a week or two now, and decided to make a custom case rather than attempting to use a pocketwatch case. I picked up a 2″ brass pipe fitting from the hardware store and  started shaping it on the lathe. It should be just about the right size…

Steampunk PDA Case - Size Comparison

Steampunk PDA Case

Steampunk PDA Case

Steampunk PDA Case

CAD Assembly

Here’s the timer interrupt that services the analog to digital converter and the multiplexing of the LEDs:

ISR(TIMER2_OVF_vect){
static unsigned char activeLine=0;
static unsigned char adcChannel=0;
PORTC=0xFF;
PORTA=0xFF;
selectLine(activeLine);
PORTC=~green_display[activeLine];
PORTA=~red_display[activeLine];
activeLine++;
if(activeLine>7){
activeLine=0;
}
switch(adcChannel){
case 0: x_accel=(ADCH-x_flat)/10;
if((x_loc<500)&&(x_accel<0)){ x_accel=0; } if((x_loc>7500)&&(x_accel>0)){
x_accel=0;
}
x_vel=limit(x_vel+x_accel,-MAXVELOCITY,MAXVELOCITY);
ADMUX=0xE1;
adcChannel=1;
break;
case 1: y_accel=(y_flat-ADCH)/10;
if((y_loc<500)&&(y_accel<0)){ y_accel=0; } if((y_loc>7500)&&(y_accel>0)){
y_accel=0;
}
//if((abs(y_accel)>1)||(abs(y_vel)>20)){
y_vel=limit(y_vel+y_accel,-MAXVELOCITY,MAXVELOCITY);
//}else{
// y_vel=0;
//}
ADMUX=0xE2;
adcChannel=2;
break;
case 2: z_accel=(ADCH-125);
ADMUX=0xE0;
adcChannel=0;
break;
default: adcChannel=0;
}

}

And the main loop:

while(1){

if((abs(x_vel)>STICTION)||(abs(y_vel)>STICTION)){
x_vel=(int)((ELASTICNUMERATOR*(long int)x_vel)/ELASTICDENOMINATOR);
x_loc+=x_vel;
y_vel=(int)((ELASTICNUMERATOR*(long int)y_vel)/ELASTICDENOMINATOR);
y_loc+=y_vel;
}
if(x_loc<0){ x_loc=-x_loc; x_vel=-x_vel; } if(x_loc>7999){
x_loc=7999;
x_vel=-x_vel;
}
if(y_loc<0){ y_loc=-y_loc; y_vel=-y_vel; } if(y_loc>7999){
y_loc=7999;
y_vel=-y_vel;
}
x_pos=(unsigned char)(x_loc/1000);
y_pos=(unsigned char)(y_loc/1000);
plotBall(x_pos,y_pos);
_delay_ms(50);

}

I just added the 3-axis accelerometer, but haven’t soldered on the supporting components. Also I still need to add the Li-Po charge IC. I am currently using the STK500 both to power and program the board.

So without further ado, here are some pics…

Mazetrix project

Mazetrix Bottom

Mazetrix Top

My board is for a project based on the Tiletoy, and incidentally not unlike the Space Invaders Button, the Awesome and 64Pixels.

Many moons ago I managed to score several 8×64 Red-Green matrix displays salvaged, evidently, from a casino display. Even though I had managed to reverse engineer them and figure out how to display nifty messages, they were just too large and too COTS for me. I removed the 8×8 LED matrices (matrixes?) and designed a small board to run them. The display is run directly from an ATMega128, using a half-H bridge on each column so I can use the entire matrix as a sensor. Additionally, I have added a MMA7260 triple axis accelerometer. Last but not least is an IR LED pointed in each of the cardinal directions, also connected to be used as an input and an output, for communicating to neighbor modules(PDF link).

The ultimate goal is to create tiles with a red maze and a green “ball” than you can manipulate by tilting, just like the good old labyrinth game. When you get to the edge of a tile, you can connect another, which will attach magnetically, and the maze will continue on the new tile.

I’ll add more updates when I start building.

Here’s a few images to satisfy the curious:

schematic

Mazetrix Layout

• Motors – move, dance, wiggle
• Audio – At least beeps and boops,  possibly recorded audio, but no extra audio hardware (like mp3 decoders)
• RGB LED Eyes – Maybe even moveable (if I have extra time on my hands)

Sufficient input to be interactive

• Location sensing – using dual color sensors and a colored mat
• Light sensors – need to know when it’s dark out, follow a light or find a dark corner
• IR obstacle detection – don’t want to bump into stuff
• IR homing sensor – to find the recharge station
• Hall Effect Sensors – locate and play with toys
• Capacitive touch sensing – how else is it going to know when it’s being petted?

Deskpet is a project that I am working on to create a small robot to live on my desk as a pet. One of the things I have learned at work is that it is much harder to build something if you don’t know exactly what it is supposed to do. So here goes; high level design goals for Deskpet:

1. The major goal for the Deskpet is to construct a pet. It needs to live on my desk and generate an emotional attachment.
   • Sufficient output to be “interesting” – If all it has is a pair of motors, I can make it dance, but it would be much easier to generate an emotional attachment if it has other methods of expressing itself.
   • Sufficient input to be interactive – I want to be able to play with my pet, so it needs to be able to sense it’s surroundings, toys and possibly me.
2. Automatic recharge – If it is going to seem alive, I can’t keep having to put it on the charger.
3. Wireless communication and bootloading – This is going to require A LOT of firmware work on my part, so it ould be easiest if I could download new firmware without even toucing the ‘bot.
4. I will not be concerning myself with availablilty or cost of components with respect to eventually making kits available. This will be a project for me.

Well, that should be enough to keep me busy……..

But not very live either. Massive problems with HTTP 500 errors.

OK. Re-installed and looks OK for now. Upgrade from 2.02 to 2.8 deserves a new theme. Maybe something with widgets?

Back to robotics…

I was working on my pan & tilt for a Defconbot (defconbots.org) when I realized it would make a great cat toy. A PC is controlling the P&T, running a random pattern with the laser pointer.
httpv://www.youtube.com/watch?v=RN6q3La3BAk

Want something more official (and expensive)? Try one from Scientific Notebook Company.

If you are looking for something more robot-related try the Makers Notebook. It includes squared pages as well as an appendix with resistor codes and all kinds of other useful information.

Finally for the ultimate in customization: Make your own notebook or reload a Moleskine. I call mine Myleskine.

The one pictured is covered in “pleather” recycled from a freebie portfolio. I recently made one for my wife with a cover made of hot pink Cordura. Also a pocket size version covered in black 300 denier ballistic nylon is undergoing “stress testing” in the back pocket of another engineer at work. So far it is holding up very well.