Week 3: Electronics production - FabISP
This week we each made our own FabISP, which is a DIY in-system programmer.
Milled PCB (with only some of the components soldered on)
- First, the board traces are cut using a Modela desktop CNC milling machine and a 1/64" bit. The outline of the board is cut with a 1/32" bit.
- After milling, wash the board with soap and water to remove oils from your fingers (which can tarnish the copper) and also to get all the dust left over from milling off the board, so that solder doesn't stick where you don't want it.
- Get all your components. I learned a trick where you write all the components down in a list on paper and use double side tape to stick the components on next to the list to keep all those tiny pieces organized.
- Solder! Work from the inside out. It's best to use the smaller tip. I first put some solder on the board, then used tweezers to position the components, then soldered them on.
- Use copper braid to get solder off of the parts of the board where solder should not be.
- Program the board using the firmware.
- At this step, you may discover mistakes you might have made. It is probably a better idea to use a multimeter to diagnose potential issues before trying to program the board. I used the wrong capacitors (which came from a mislabeled components drawer). I had to desolder and resolder on the right ones.
- Once the board is programmed, desolder the jumpers (SJ1 and SJ2).