Assignment 06 — Computer Controlled Machining

07. INPUT DEVICES

GROUP WORK

Softwares: KiCAD, ArduinoIDE, Mods, Gerber2Img, Illustrator, Rhino
Devices: SRM-20 PCB Mill, EpilogLaser, Xiao RP2040, MFCR522
Files: 8.CatTarot.3dm, 8.TarotTutorGerber.zip
ChatGPT: RFID Scanner Code Prompts

This week we worked with the oscilloscope again to look a distance sensor. Using the two prongs we probed at different areas on the sensors to see the different signal changes between different pins. Thanks Gert!

For this week’s assignment, my goal was to understand how to use an RFID reader to read information. This was mostly for my final project, as I will be trying to use this type of system for my tarot deck!

My second, more ambitious goal was to make a mini prototype with few test cards using materials I could find around lab and create a simple tarot dictionary that pulled up small meanings upon scanning the cards.

First, a confession: I never ended up having the time to test out my board past assembly for electronics production week, so a lot of my troubleshooting and learning came this week!

My initial problem was that I soldered all of my header pins to the back of the board (dumb mistake...) so I had to remove the solder from the pins but it proved to be the bane of my existence trying to remove enough to wiggle the 01x07 long pins out!

I ended up trying a few different wrapping methods with the copper braids until I finally got enough off to wiggle my RC522 Reader off my PCB. And finally I was left with an electrically connected board! I tried being super diligent while soldering initially so that I wouldn’t have as many board issues like bridging to deal with and I think it paid off!

I then instead of resoldering the RFID reader, I decided to use female adapter cables to connect it to the board so it could function more like the final piece.

In my initial research into how to use RFID tags and what kind of reader + tag system would work best for me, I found my RC522 RFID reader kit on amazon and these NFC Tag stickers for my tags.

I thought the RC522 would be the best to use because it’s a high frequency RFID reader (reads a wide range of frequencies, 3-30MHz), and easily connects to 13.56 MHz frequency tags, which goes well with these ultra thin (and cheap, bless ) Near-Field Communication (NFC) tags stickers that could easily adhere to the back of a tarot card. They can also store up to 504 Bytes of memory, which is good for storing short tarot meanings and messages.

First, I downloaded the MCFR522 library by the github community. Then I used ChatGPT to write a rudimentary code that just scans a tag’s ID number and displays it both on the serial monitor on the ArduinoIDE and on the display screen.

Then, I wanted to learn how to load individualized information on NFC stickers! So I also used ChatGPT to help me write a code that could overwrite and add text as stored data onto any NFC card by clicking a button.

To start, I wanted to make a few different cards from the Major Arcana deck (22 of the cards, they represent more major life lessons and milestones) by laser cutting and engraving so I chose a central theme that could be easily engraved: Cats!

I pulled 9 major arcana cards from a few different cat tarot decks and stickers from artists across Pinterest and RedBubble and put them in Adobe Illustrator.

Then I used Image Trace to create simplified vector images of each card and sent the deck to Rhino.

In Rhino, I exploded the SVG in order to clean up the file from warped lines, unnecessary details, and card size! To clean up, I deleted double lines and outlines, and edited specific sections within the art using Rhino’s spline curves until it was to my linking. Lastly, I set the hatching, and determined the cut and engraved layers.

I laser cut it on this beautify two toned 1/16” paper that my friend had left over from a studio project, and I engraved a test first, then the rest of the cards. The dark color could be rubbed off, so I tried with the death card the outcome was okay...? Then I stuck an NFC sticker along the bottom of each card.

But upon trying to program each card, my Arduino stopped responding and turning on... so it was onto a new PCB... Thank you to Adin who taught me how to trouble shoot with the milling machine! This was by far my chillest cut.

Sooooooo I couldn’t find a new Xiao RP2040 in shop last night, and I was told to come in tomorrow morning, so if I manage to do that and update the data for each tag in between my morning classes, these two images should be there! But don’t count on it.

PCB TROUBLESHOOTING

RFID READER ID PULL UP

TAG REWRITING

MAKING TAROT CARDS

RE-MILLING PCB

writeTagMessage(“blah blah blah”);
is the command for rewriting a chip and use if statement for button prompt

TAROT CARD MESSAGES PLANNED

The Tower -------------- catastrophic change, destruction
The Lovers ------------------- major decisions, relationships
Death ------------------ major ending to new beginnings
The Fools ----------------- leap of faith, new journey
Temperance ------------------ balance, moderation, harmony
The Chariot ---------------- victory, triumph over obstacles
The Hermit ----------------- introspection, seeking inner guidance
The Moon --------------- intuition, the subconscious
The Word --------------- success, end of cycle, harmony

TRIALS & TRIBULATIONS

LESSONS LEARNED

I had some issues trouble shooting the RFID reader... it took a while to get it to be able to read the chip data, but it turned out that I had it wired in the opposite direction... always check your connections and pins before soldering! Thankfully mine was just using connector wire so it was an easy fix.
I did end up accidentally ripping off my audio amplifier and speaker (never used... tune in next week!!) And had to learn how delicate that top lining of copper is the hard way....

Make sure you have extra parts, and get a box to hold everything so the device doesnt break in transit, and if it does, you can replace parts. I think every week I end up not having enough/the right materials so I think I need to start coming in as early as possible to pick up my materials (and an extra...) for every part regardless of when I’ll have time to work on it.
Building sucessively on this assignment was the best possible decision I could’ve made... no more starting super ambitious and then walking away with little progress...

Final Board Image

Tarot Card Implementation