This week, I set out to test my circuit with 125 kHz bit tag cards. I hit a few bumps at the beginning of the week, as the circuit wasn’t showing any signs of card detection. I tested the bit cards with our commercial RFID reader, and both worked, so the issue was my circuit. I used the oscilloscope and ADALM to monitor the output at various points in the circut, and with the professor’s help, figured out the issues: the input of the circuit was incorrectly grounded; the DC power supply to the op amp was uncalibrated; and because of the DC power supply being a lot higher than I thought, my Arduino was damaged. I fixed the first two issues in the lab, and got addtional Arduinos from my teammates.
This week of debugging did push me back a bit, but I expect to be ready for demos next week. Sophie and Dina set up the RPi during the week, which I originally expected to handle, so overall I’m in a good place.
After demos, I will begin the process of soddering the now correctly working circuit. I’ll first look into the possibility of changing my circuit so that it can read CMU IDs, but since I still don’t know exactly what frequency the cards are, it’ll be a bit of guess and check work. I think if I can’t find it within a few days, it’s not worth the delay in progress.