6. Electronics Design

This week of Fab Academy is all about designing and milling your own PCB with a microcontroller and successfully making it do something. In this case I will be using the MicroPython code from Week 4 to turn on LEDs using a Seeed Xiao RP2040.

Simulating Circuits

Next I needed to learn about PCB design. This led me to KiCad. I started a first test project with the schematic and PCB files.

It took a while to get used to the interface of the schematic editor so this attempt was more about understanding how to add components and make connections.

The experiment continued in the PCB editor. It would take a few more steps in my learning process to understand how to utilize these tools.

Looking over the MicroPython code in Thonny with Alie, a member at Moonlighter FabLab, I was able to understand more about connecting the RP2040 microcontroller to Thonny and manipulating the code.

She was also a huge help when we assembled the components on a breadboard. This was my first time seeing a physical circuit layout on a board presented in a clear and logical way. I really appreciated her assistance.

Link to YouTube Video

This Youtube tutorial taught me how to use the tools and symbols in KiCad.

I returned to KiCad to create a proper schematic of the PBC. I still wasn’t fully confident but I followed the logic of how electric currents flow. My logic may have been a little off because I still think I put the resistors in the wrong place.

We use Bantam milling tools at Moonlighter FabLab to produce our PCBs. To use these tools I needed to install the desktop application for my Windows pc.

I found these bits for the mill thinking they were the correct type for PCBs.

You can see how sharp and pointed the tips are.

Next I had to prepare the Bantam

I loaded the bit by loosening the grommet and inserting it according to the instruction in the application.

Then I set up the interface for the bit type, material and positioning.

After uploading the Gerber file of my PCB from KiCad, I was able to place it on the material for the best layout to be cut.

This took some trial and error as I was figuring it out for the first time.

It was finally time to cut my first PBC. The program tracks the mill as it follows the tool path.

The first cut failed because the traces were too thin which caused them to fray. The bit I used was also unable to cut the PCB out fully.

I went back to KiCad to increase the trace thickness and uploaded it to Bantam.

This cut went much better but still was not able to be cut out completely.

Here you can see the difference between the cuts.

I used a scroll saw to finish cutting the boards out.

I used the KiCad design to solder the second board.

Using a Multimeter, I tested the traces because the board did not work.

Resetting for another attempt, I found out that I was using the wrong Bantam and the wrong bit.

Setting up the new Bantam Tool with a 1/32” flat end mill worked much better.

The final cuts were clean and had wider clearances. This flat end mill was also able to cut through the board eliminating the need to do post processing.

The difference between the boards was very clear as the thicker clearances made the PCB look much cleaner.

Soldering the final board was much easier and went very quickly.

Here you can see the working final product.

Downloadable Files

Group Projects