Microcontroller BootCamp (3) Serial interface and A/D converter

摘要

This instalment focuses on the analog to digital converter, which is effectively a voltmeter built into the microcontroller. However, it does not have a pointer or a display, so you have to do a bit of work to be able to read the measurements. The A/D converter simply supplies data. In order to be displayed somewhere, this data has to be transmitted. That's where the serial interface comes into play. Although most PCs nowadays have dispensed with the traditional serial interface, it is still widely used in the microcontroller world. This interface was originally developed to transfer serial data over a conductor. The individual bits obediently travel down the wire one after the other. The bit tinning is precisely defined so that the receiver can make sense of the serial bit stream. A commonly used data rate is 9600 bits per second, which is also called 9600 baud. In addition to the eight data bits of each byte, there is a start bit and one or two stop bits. Each data bit is present on the wire for an interval of approximately 100 μs (at 9600 baud).