Stuffomatic – manual “pick and place”

November 4th, 2014. Posted in: Building, therevox.

I finally got a chance to test out this little invention I call the “Stuffomatic”. It is used for stuffing circuit boards with components by lighting up the correct part bin. It is activated by a footswich, and uses a Teensy 2.0, buzzer, OLED 2×16 character display and a MAX7219.

While manually stuffing and hand-soldering Therevox circuit boards, I wanted something that would speed up the process and cut down on errors. On first test, the stuffomatic seems to speed up the “stuffing” process by close to 30%. Grabbing a component directly out of the lit bin is also a lot less prone to errors, compared to the normal way (reading the reference off the board, cross referencing it with the Bill of Materials to get the part value, find the right value part bin, grab the part).

The stuffomatic advances to the next part when a footswitch is pressed. I used a buzzer to make a small “click” noise when the footswitch is pressed for some audio feedback. There is also an “up” and “down” switch on the stuffomatic to quickly go through the list of parts.

The only problem with this project was that the Teensy couldn’t store the entire BOM (bill of materials) in memory. Instead, larger amounts of data need to be stored in PROGMEM which requires very messy code to declare the variables. To get around this, I wrote a PHP script that reads a CSV file and outputs the PROGMEM variable declarations as a 2 dimensional array. This also makes it easier to recompile the stuffomatic code for different projects.

On the front of the stuffomatic is a “note” LED to draw attention to the display if there is a special note or instruction being displayed. The stuffomatic can show messages like “flip board over” or “solder”, or a specific component might have a note with it.

So far I’m happy with the stuffomatic, it did take a lot longer to finish than I expected, but building it was more fun than stuffing circuit boards.