An Introduction to Microcontrollers Part Ⅳ: Serial Comms for Data and Devices

摘要

Circuit designers rely on bit-by-bit serial communications between microcontrollers (MCUs) and external devices because they require fewer I/O (input/output) pins than parallel data transfers. A12-bit analog-to-digital converter would need 12 data lines and several control signals. The same converter with a serial interface might need two or three signals. Of course serial transfers take longer, but engineers often want more available I/O pins rather than faster communication rates. Many MCUs include universal asynchronous receiver-transmitter (UART) hardware "blocks" that handle all control operations for bi-directional 8-bit serial communications. The word asynchronous refers to the lack of a clock signal between a transmitter and a receiver. MCUs also may furnish hardware blocks for other types of serial communications that require a separate clock signal.