The RS232 Serial Port

Even though the concept of the serial interface has been around for years and USB is becoming more and more established, there are still many devices that need to be interfaced with a serial port, for example, measuring instruments and GPS receivers. In addition, the Bluetooth standard defines several protocols (profiles) to access different devices like head sets and printers, and it also has a communication profile via Bluetooth named Serial-Port. Some serial-to-Bluetooth adapters exist already. If such an adapter is connected to the serial interface of the microcontroller, a .NET Micro Framework application can communicate wirelessly with a PC, PDA,smartphone, or other microcontroller (see Chapter 7).

Together with the serial interface, you quite often hear the terms "UART," "USART," and "RS232." UART and USART are names for the serial hardware component, the Universal (Synchronous) Asynchronous Receiver Transmitter. The RS232 standard describes how data will be physically transferred over the cable. Further standards are RS422 and RS485.