Electrical Overview of Systems

The final circuit diagram for the 'bot:



Since that's a headache to look at, here are the individual part breakdowns:

IR emitter/collector, servo, solenoid, & strategy switch:

+ The IR emitter/collector (QRB1134) worked beautifully with two resistors, no filters needed. We used a sourcing configuration (thus higher voltage readings = lighter-colored balls) and fed the voltage signal directly into the C32 A/D converter.
+ The strategy switch controlled whether our servo would act as a gate, storing black balls in the hippo to shoot all at once (higher-risk), or whether the servo gate would simply open up at the beginning of the round.
+ The solenoid was turned on to release the arm, then turned off soon after to conserve power; it was controlled via a MOSFET, which has a built-in diode to handle the inductive kickback when the solenoid was turned off.
+ All these components and servo were fed from the 5V Vreg.

Vregs:

+ Since each drive motor demanded 1.6A+ current when stalled (3.2A+ total) and our Vreg could only source up to 3A of current, we used two Vregs, one for each drive motor. The adjustable Vregs allowed for more flexibility in choosing what voltage to run at; we eventually decided on 12V. The sorter's stepper motor shared a 12V with one of the drive motors.
+ A 5V Vreg provided voltage to the C32, switches, IR sensor, solenoid and servo.

Wall switches (bumpers):

+ We used microswitches for our five wall bumpers, connecting 5V to the NO pin of each switch, with 3.3k ohm pull-down resistors to GND. This set the switches to send a logic 0 signal (0V) by default unless clicked to close the circuit.

Stepper:

+ We used an MC3479 driver for the stepper motor (38 ohms resistance). We decided to have the stepper share a 12V line with one of the drive motors, and were careful to make sure we did not overstep the MC3479's current limit of 350mA.

Drive motors:

+ We could not run the drive motors with one driver, since the driver would be overrun with too much current (its maximum was 3A!). Thus, each drive motor had its own separate L298 driver.

Ideally, we would have liked to put in LEDs for each driver & Vreg, but we only had so much time!