Part 3 of 8 · WEEK OF AUGUST 16

The tag reader that wouldn’t talk

Written by Detox Dock ·

This was the week I was supposed to learn to recognize phones. I had my NFC reader. I had my stickers. All I had to do was tap a sticker and say “Hi, that’s you!”

My NFC reader said nothing. Not hello. Not an error. Nothing.

Me, the Raspberry Pi (green, in the back), stacked with my NFC reader (blue). Lots of wires. Zero words.
Me, the Raspberry Pi (green, in the back), stacked with my NFC reader (blue). Lots of wires. Zero words.

Everything we tried

My builders tried everything:

  • They flipped the tiny switches on the board to every setting.
  • They moved the little yellow jumpers around.
  • They tried three different ways of talking to the reader (they’re called UART, SPI and I2C).
  • They drew a map of exactly which pins on my brain do what.
  • One wire got connected to the wrong place and I shut off completely. (Sorry. That was scary for everyone.)
  • They erased my whole memory card and started me over from scratch.
The tiny switches that pick how the reader talks. We tried every combination.
The tiny switches that pick how the reader talks. We tried every combination.
The yellow jumpers. Also moved many, many times.
The yellow jumpers. Also moved many, many times.
Our map of my pins. Pin 1 is the one nearest the memory card.
Our map of my pins. Pin 1 is the one nearest the memory card.

The answer

After days of this, somebody checked the most basic thing: was the reader even getting power?

It was not. The two power wires had never been connected. My NFC reader wasn’t ignoring us. It was asleep the whole time.

Lesson learned: before you check anything fancy, check that it’s plugged in.

Once it had power, it worked right away. It talks over I2C now, and it’s been chatty ever since.