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Assignment 4

Brief

  • Make and test a microcontroller development board
  • extra credit: make it with another process (not completed but have some links :D)

Soldered Dev Board

Group assignment link

Make and test a microcontroller development board

For this weeks assignment we were going to mill a custom breakout board for the Xiao RP2040. Claire prepared a quick board that was a derivative of the board she designed in week 8. We would keep the same schematic and only change the board outline.

Exporting from KiCAD

We printed out the SVG's from KiCAD, and modified them in Inkscape to make them compliant for Mods our G-Code generator for the SRM-20.

Mods Example screenshot

Generating G-code

We had to fix a couple things in Inkscape: Do this again and pass into mods :D Sorry past Liam

  • Ensure the edge of the SVGs is uniform across files,
  • Remove internal holes from the Top Copper layer, this is handled by the drilling pass.
  • The board outline should be white on the inside
  • The holes should be black
  • The traces and pads should be white

With the SVG's formatted we could pass them into Mods and generate G-Code

### Milling the board

Like in the group project we do the following: 1. Zero the machine 2. Move our job to the best spot (zero again, leaving whitespace) 3. Start milling process and swap bits for outlines

Testing the board

Now we have the PCB but how can we make sure it will work?

First tests

Before we even get the PCB off the mill we should make sure the traces arent shorted. Using a multimeter in continuity mode test the adjactent pads arent shorted.

We might have to re-mill the traces a bit lower.

Once we're all good we can remove the PCB - Thankfully we were!

Soldering

Since the board uses the top copper and we milled the top copper... we would have to solder extra long headers or reverse the Xiao. Both not great options so something to fix up for future PCBs!

I have quite a bit of experience soldering so zipped through this...

IMAGECAPTION

Me soldering Picos

...having soldered over 1000 Raspberry Pi Pico boards using drag soldering.

Using the Microcontroller

3 tests were going to be performed (In Assignment 6) 1. Does the onboard LED work? Set the pin high and low, observe it turning on and off 2. Does the onboard button work? Read the pin, observe the serial output outputting the state 3. Do the GPIO outputs work? Wire one to another, set one high and read the other

Different Manufacturing Process

Shoutout to this master of prototyping: Techniques and Strategies for Building Electronic Circuits | Leo's Bag of Tricks

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