Introduction

Contactless building access cards and automotive keyless entry fobs both rely on exactly this kind of technology to identify themselves wirelessly. In this experiment, an MFRC522 RFID reader module is wired to the STM32F070RB over the SPI bus, and the microcontroller reads the unique identifier of a nearby RFID tag or card, printing it over UART the moment it is detected.

2. Scope

This experiment covers configuring the STM32's SPI1 peripheral as a bus master, performing the MFRC522's register-based soft-reset and antenna configuration sequence, and executing the request and anti-collision command sequence needed to retrieve a present tag's unique identifier. This is the first experiment in this series to use SPI, a third major communication protocol alongside UART and I2C.

3. Prerequisite

3.1 Hardware

• STM32 Nucleo-F070RB development board

• MFRC522 RFID reader module

• At least one RFID tag or card compatible with the MFRC522, 13.56MHz, MIFARE compatible

• Breadboard and jumper wires

• Micro-USB cable

• PC with PuTTY

3.2 Software

• STM32CubeMX (standalone)

• STM32CubeIDE

• ST-LINK USB driver

• PuTTY, or an equivalent serial terminal application