Once again, wow. I've had to learn 90% of everything I know about computers, computer hardware, programming, web design, Photoshop, 3D Studio Max, etc. myself. I haven't taken any school computer class yet that I have actually learned anything in, they all teach very basic stuff, stuff that I considered below me.
However our schools robotics team is completely different. The first programming lesson they gave use showed us how basic binary worked in 8 bit applications and how PWM variables work in the Vex kits (and all robotics). My point is simple, I absolutely love the FIRST program. My brain has opened up and sucked in every drop of information it can from our schools robotics program. I'm basically the leader of FTC team #509 and will most likely be doing a large portion of the FRC bots programming this year.
So theres a bit of info about me. Back to the Dell Bot project...
After looking at the pages you guys showed me I've decided to attempt to build my own serial based motor controller from this article:
http://www.rentron.com/SerialServo.htm
The main motivation is price and learning more about the basics of how this stuff works. I like getting knee-deep in these projects, just how I work. The idea is to build two of these and program them independently. One will power the components on the base (wheels, etc) the other will handle the arm and claw we hope to build.
One question about that article, the diagram shows a PIC:
http://www.rentron.com/Files/Stamp/pc-servo2.gif
I've located this PIC and priced it (around $5, not bad) but won't I need to program the PIC itself before it does anything?
Another small question, the diagram shows one pin from the microchip connecting to each PWM output, well it's my understanding that PWN cables have three wires (black, white and red). If the microchip only outputs to one wire then I'm guessing that it's the white one and that black and red are battery and ground?
Also, what is a 4MHz Ceramic Resonator? I've looked one up, a little $1 part that I've seen before but what does it do?
On the subject of the battery. I've done my homework on car batteries. I knew that the batteries weren't designed to be completely discharged and I will take care to ensure that the battery we use won't get that low. But I didn't know how long it would last, please trust me 8 hours is PLENTY
However two questions here:
- I need a way to recharge the battery without a car, I'd like to build a battery charger that could charge it using a household 120V AC plug. How simple would that be? I assume I can't just plug one end of the plug to the + and - ends of the battery.
- I'd like to be able to make something, perhaps a small LCD screen that could tell me the amount of charge left in the battery. So that I never drain it all the way and so that when it's charging we know when it's done. I believe the drop in voltage is how you can tell the amount of charge left? Like when the Vex controllers show voltage on the little LCD.
Again thanks guys, I know this project is a big one but I feel that the experience and end result is well worth the effort. I'll make it a point to post pictures later and I may even make a little web page dedicated to the project so that others can have a reference.
-Smartkid