RFID reader on a Raspberry Pi
Counting Pumpkins

© Lead Image © raspberrypi.com
Inexpensive components for the SPI interface let you upgrade a Raspberry Pi 4 to a display system for zero-contact RFID-based data acquisition.
Radio-frequency identification (RFID) tags have become indispensable in industry and government, as well as the wholesale and retail spaces. The inexpensive transponder chips can be found on clothing labels, identification cards, and credit cards. Armed with just a Raspberry Pi and an RFID kit, you can read the data from these chips and view it on a display.
In this project, I read serial numbers from RFID tags stuck on 3D-printed pumpkins – a slightly different kind of detection task. To do this, I connect an RC522 [1] RFID kit and a 1.8-inch ST7735 serial peripheral interface (SPI) thin-film transistor (TFT) display [2] to a Raspberry Pi 4. Together, the two modules can cost less than $15 (EUR15, £14) in online stores. The pumpkins contain simple RFID tags [3], also available for very little cash. Although at first glance the project seems clear-cut and sounds as if it should work right away, check out the "Mishaps, Misfortunes, and Breakdowns" box to find out what can go wrong.
The circuit diagram in Figure 1 shows how the modules connect to the Raspberry Pi, along with two pushbuttons and LEDs for testing purposes. The KiCad layout of the project is included in the download section of this article [4].
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.

News
-
System76 Releases COSMIC Alpha 7
With scores of bug fixes and a really cool workspaces feature, COSMIC is looking to soon migrate from alpha to beta.
-
OpenMandriva Lx 6.0 Available for Installation
The latest release of OpenMandriva has arrived with a new kernel, an updated Plasma desktop, and a server edition.
-
TrueNAS 25.04 Arrives with Thousands of Changes
One of the most popular Linux-based NAS solutions has rolled out the latest edition, based on Ubuntu 25.04.
-
Fedora 42 Available with Two New Spins
The latest release from the Fedora Project includes the usual updates, a new kernel, an official KDE Plasma spin, and a new System76 spin.
-
So Long, ArcoLinux
The ArcoLinux distribution is the latest Linux distribution to shut down.
-
What Open Source Pros Look for in a Job Role
Learn what professionals in technical and non-technical roles say is most important when seeking a new position.
-
Asahi Linux Runs into Issues with M4 Support
Due to Apple Silicon changes, the Asahi Linux project is at odds with adding support for the M4 chips.
-
Plasma 6.3.4 Now Available
Although not a major release, Plasma 6.3.4 does fix some bugs and offer a subtle change for the Plasma sidebar.
-
Linux Kernel 6.15 First Release Candidate Now Available
Linux Torvalds has announced that the release candidate for the final release of the Linux 6.15 series is now available.
-
Akamai Will Host kernel.org
The organization dedicated to cloud-based solutions has agreed to host kernel.org to deliver long-term stability for the development team.