Arduino
http://www.instructables.com/id/Make-your-own-Arduino-on-Veroboard/
Try using an lcd with SPI, they're cheap on eBay.
Pro-Mini Notes
Red board, no plastic. Connect to Arduino pro mini with tops of circuit boards facing the same way. Open Arduino IDE as root (or it can't access the serial port). Programmer is "ArduinoISP"
Power is supplied to the Raw pin. Do not connect power directly to Vcc pin. It's supposed to handle up to 12V, but I tried that and the board died very quickly, so don't do that again. Actually, I think I had just above that (12.3v) and 12v is a hard limit. I'm pretty sure the on board regulator is linear, so probably shouldn't give it more than 7V.
- Sparkfun: 3.3v 8MHz
- Other: 5v/16MHz
Systems
Power
Step Up
- $2.07 : 3v3 step up
- $0.50 : Battery Clip
Can run off a single AAA battery, good for lightweight.
Step Down
- $0.40 : Battery clips
- $0.43 : Step down regulator
Cheaper, lasts longer. I need to try using just the clips to hold a battery to board. Can also swap out the 4xAAA for a 9V. Lasts even longer, and probably lighter overall.
Display
All options are about $2. The 16x2 is a bit larger and more readable but limited to text. The 5110 is more flexible but kind of small.
Setup
Pro-Mini
$4.62
I really liked these at first, but now that I'm getting a better grasp on the stand-alone circuits, it's not as good. It takes us just as much space as the dip would, the analog inputs are hard to get to.
Stand Alone Tiny85
~$1.50
Limited IO, but that can be expanded with 74HC chips. Good for simple, small projects.
Stand Alone Mega328
~$2.00
Full power Arduino, fairly compact. I think this is the best option.
Setups
- $1.00 : Power; 9v | 4xAAA step down
- $2.00 : Display
- $2.00 : Mega328
- $0.13 : Small Perf Board
$5.13
- $2.50 : Power; AAA step up
- $2.00 : Display
- $2.00 : Mega328
- $0.13 : Small Perf Board
$6.63