Agorobots - Friday plan

Using the motor driver chip to drive motors.

EN (enable) portsMust be high to turn on the chip
A portsInputs
Y portsOutputs (connect to motors)
GroundConnect all ground pins to ground (0V)
VCC1Connect to 5V
VCC2Connect to 6V for full power
Check with me before plugging this one in, and please put a bit of masking tape on the chip for saftey; it can explode!

Using motors

You will get one Tamiya twin-motor gearbox kit. There are two ways to put the kit together; with a 58:1 (fast) gear ratio or with a 203:1 (slow) gear ratio. The slow version will probably be fast enough for us, so use that one!

Using our water model from before, think of a motor as a big waterwheel in the river, that spins when water flows past it. What happens when you suddenly try to stop the flow of water? The wheel keeps spinning for a while, and pumps water through your circuit. (This is not just because there is a physical axle spinning here, but mainly because of the magnetic fields created by the motor coils.) This extra pumping can cause flash floods (spikes) of 50 or 100 volts that can do damage to the rest of the circuit. How do you deal with these spikes? The same way Champaign-Urbana dealt with the boneyard flooding "problem" - build detention basins. Capacitors are detention basins for electricity: they can store a lot of extra charge and release it when needed. Put these all over your circuit, especially right on the motor terminals (I will show you how). The direction of the big capacitors is important - put them in so that they will get voltage in the right direction most of the time.

Putting it all together

Think of something you want your robot to do (something simple is best for your first robotics project!) and plan out a program for it. It may help you to draw a flowchart on a piece of paper. Then, using what you have learned about programming, motors, and sensors, build it!
Go back to the main page.