Final PCB Design

Okay, so I completed my PCB design. This was quite the puzzle, trying to stay within the dimensions of an arduino "shield" and cram on as many components as possible. A "shield" is a circuit board that has rows of pins aligned to plug directly into the microprocessor (that's the rows on top and bottom of the boards pictured below).

Whatever goes between the rows of pins on a shield is up for grabs. The way I am thinking about this is that the shield will be fastened to a project and wired into its motors and sensors, and the arduino will just be popped on when in use – like a portable brain. This way I don't have to buy a new arduino for every project I try, but I can also revisit projects pretty easily.

So, my choices for this PCB center on an "H-Bridge," the big chip in the center that can independently control two motors in two directions. This could be two wheels/tracks, like a tank, or a combination of steering and speed, the results could be similar: This would be suitable for a vehicle. The middle pins on the H-bridge go out horizontally to the motor connections (one on each side) and I have given each connection two LED lights that can indicate when the motor is turning one direction or the other. Aside from looking cool, the lights will also help when troubleshooting the connections and code.

Other inclusions are two separate LEDs that can be dimmed. Yes, that's six LEDs so far! And beyond that, there is optional space for two small pushbuttons and a potentiometer knob. Maybe a button would set mode, the knob could set speed or sensitivity, and the other button could start and stop. Just an example. The knob would use one of the six analog inputs (it's optional), and – because some of the pins are multi-purpose – could leave some ratio of seven more inputs/outputs when combined with two unused digital In/Out pins.

I'm thinking that one motor could control an array of distance sensors that pan back and forth, mapping the surroundings to a matrix (spreadsheet) in the arduino memory. Perhaps that sensor array is mounted to a steering wheel, so after the sensing it will control direction while the other motor controls driving forward/backward. I might include a static sensor on the body of the vehicle that compares the map with the actual heading. By switching between these functions quickly, I think this system could appear to smartly navigate toward either the closest object or most open route. I think I can also have the vehicle protect itself from driving off a cliff.

Oh, and we'll see if the screw holes will work for securing the board [with arduino] to the project. I think two are so close to circuit tracks that they would contact and possibly short something; the two in the corner seem to have enough room, so there will be multiple examples from which to learn.

I'm planning to cut this board on our CNC mill tomorrow, so I'll post some pictures of the process after that. Then, I will have a lot of soldering ahead of me. ... 

... A WHOLE LOT of soldering. 

Until then: stay classy.