The project takes an MRFC-522 RFID module and explains how to interface it to an Arduino. In this case the Arduino in question is an Arduino Pro Micro chosen for its ability to be a USB host.

PD Micro is the first Arduino-compatible board with USB Type-C Power Delivery, which allows your project to make use of voltages from 5-20 V. It’s ...

PD Micro is the first Arduino-compatible board with USB Type-C Power Delivery, which allows your project to make use of voltages from 5-20 V. It’s ...

In addition to the 3D printed frame and Kailh switches, there’s also an Arduino Pro Micro onboard to communicate with the phone. Rather than use USB, the keyboard is wired to the I2C accessory ...