Significant progress has been made on my PComp final.

PComp Final Progress from Tom Arthur on Vimeo.

What's working:

  • Counting coins & activating coin sorter mechanism
  • Reading NFC tags
  • Writing & reading saved state of amount of money in machine to SD card
  • Getting world time to log the time coins are collected
  • Displaying BMP images on LCD
  • Displaying data on OLED display

Counting coins

This is working 100% after replacing the blown out sensors.

Reading Tags

The tags are a pain because the information is encoded in individual bytes. Or something. But I successfully wrote the tag information to the OLED display.

Write/Read SD card for saving amount of money

This was a HUGE pain. Reading saved data from an SD card file and making it into something useable took forever. But it's working. Even if the counter looses power, it doesn't forget what money you have inside.

Logging the time coins were collected

In theory, logging the time will help check for when things go funky. I think this will be more useful for the web component. Or might just end up being unnecessary.

Displaying BMP images on LCD

I also had major problems with this one. Basically the Arduino doesn't like dealing with two SD cards, especially when one is on the ethernet shield. After trying extensively to get both to work, I discovered I could serve the BMP images from the ethernet shield SD card. So that's working now too.

OLED Display

No issues here. Wish it was bigger.


What still needs to be done:

  • Final Enclosure
  • Proximity sensor or button for starting coin counter
  • Code for reading tags & showing what you can buy
  • Choosing trinket & writing individual tags
  • HTTP requests to server for web component
  • Images for tags to show on display

Final Enclosure Status

I laser cut a larger cardboard box and purchased matte black acrylic for cutting the final version. Still unsure about the location of the displays. The LCD has a bad viewing angle but my laser cutting skills are not yet good enough for me to make anything more complex than a box.

Coin sorter proximity sensor

Continuing the theme of blown out sensors, I think I screwed this one up too. I was using a Sharp IR distance sensor. Not sure if I'll try buying a new one or use something else.

Code for reading tags

Reading data from NFC tags seems to be a pain. Not sure if I'll be able to get data pulled from the tags or if I will end up having the details stored on the Arduino / web and just look up the tag ID.


Does anyone have a good source for miniature items?

HTTP requests

I have a basic understanding of how this works and will learn more on thursday in my Comm Lab web class. Shouldn't be an issue since it's not a mission critical component.

Images for tags

Images can take up to 4 seconds to draw. It's really slow. Not sure if I'll stick with one image or use a different one for each tag at first.

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