This is the final post about the rover, I promise. In addition to the changes made to the electronics box, we also needed to get data from the wheels. Each wheel is a self contained unit with a battery, motor, and speed controller, which is sent pwm signals from the mbed. We needed to get the power draw from each wheel and this is the board I designed to do it.
Last summer I started working with the rover team to modify the rover to be used for another research project. The original rover did extremely well at the competition but they were working under tight time restrictions and almost all of the work was done by undergrads. That meant there was a lot of work needed to fix and modify it.
This is a super simple post to encourage you to use schematics when you use EagleCAD. When I learned, the person who taught me didn’t use schematics so I learned to not use schematics and just design the board using packages. At first I didn’t know any better and blindly accepted the occasional error that happened because I switched pins. It was especially difficult when the chip package is rotated from the documentation and gets even worse when it’s also on the bottom of a board. But in the last few months I’ve been burned several times by this and I’ve seen the light. From now on, I’ve started using schematics for all my boards. Compared to just designing a board from packages, doing the schematic first is a lot more work. But if you verify the package and schematic when you make it, it eliminates almost all of the errors. And while making the schematic and device is a pain in the butt, it makes laying out the board a lot faster because everything is already connected by airwires. Anyway, that’s my advice, take it or leave it, but I hope it helps somebody avoid the mistakes I made.