Make a proposal for a final project
PCB design, fabrication, assembly
Waterjet cutting, NC milling
Microcontroller programming
3D scanning and printing
Input devices
Molding and casting
Output devices
Composites, joining
Networking and communications
Final project


Output Devices

The assignment of this week was to use an output device to do something through a microcontroller. Unfortunatelly I didn't manage to succesfully make mine do what I would like it to do =[: I burnt a board, broke an endmill, and spent a lot of time trying to find a good layout without too many vias. I wanted to work with motors as an output device, and being undecicive choosing between stepper or DC motor, I spent unproductively my time lingering between those two options. My first idea was to build a light following robot. My second idea was to combine the hello.stepper example with the hello.ftdi to control a sliding head/gantry with the keybord using a stepper motor. None of those two was finished.


I started with Neil's hello.hbridge to get familiar with controlling dc motors. It took a while to understand how an h-bridge works and how the c code controls it, but at the end I got a basic understanding of it. Here is what I did:


Next, made the hello.stepper example to understand how to move a stepper motor. Although the theory is easy to grasp, the code was not so clear to me. I manage however to tweak the code to do other meaningful things such as changing the speed/direction of the rotor.



Next, I decided to make a Fabduino, following Ed Baafi's instructions. I wanted to have a custom made cheap arduino-compatible board as an emergency plan in case all other things don't work. We bootloaded it with Ed and it works nicely!


Next, I decided to combine the FTDI example witht the stepper example to make a stepper mode that I could control with my keybord. I think my schematic is good, but I couldn't find any layout without overlaping nets/traces, so I had to make vias. Unfortunaltelly I wasn't careful with my tolerances and as a result


Finally, I tried to make the light-following robot. I combined my previous design for the Optical Encoder that ises two photo transistors with two H-bridges. It was impossible to avoid crossing traces, so instead of using vias I decided to brake to board into two boards and connect them with ribbon cables. Sowhere in the process I screwed up with my schematic cause my photodiodes don't give any input in my microcontroller! Moreover, when I finished the board I hooked up the power in the wrong way and I burnt my voltage regulator and most probably my tiny44 too, cause the entire board was smoking and smelling. Phew! Moreover, during desoldering of the tiny44 I pulled up the copper traces destroying my board. Here is my schematic and my two boards witht the tiny55 missing after desoldering it.




Next Steps

For the next steps I will complete the light following robot project and get back to update this page. Stay tuned.