In order to communicate with peripherals and other microcontrollers, a number of de facto standards are well established in the embedded world. Some of the external pins of the microcontroller can be programmed to carry out communication with external peripherals using specific protocols. A few of the common interfaces available on most architectures are:
- Asynchronous UART-based serial communication
- Serial Peripheral Interface (SPI) bus
- Inter-integrated circuit (I2C) bus
- Universal Serial Bus (USB)