Introduction to USART in STM32 USART stands for Universal Synchronous/Asynchronous Receiver/Transmitter. When I started working with STM32, I thought USART was just another name for UART - basically a serial port for sending and receiving data. But I was wrong. USART in STM32 can actually do more than that. From what I’ve learned, it can work in different modes: Asynchronous mode (UART) - for normal serial communication Synchronous mode - with a clock signal, similar to SPI Smartcard mode - for ISO 7816 smart cards LIN mode - for automotive applications IrDA mode - for infrared communication Hardware flow control - using RTS/CTS pins I don’t have experience with all of these modes. In this post, I’ll just share what I know about serial communication and smart card interface. I’ll also show how I used USART to build a simple SIM analyzer. ...