It has been a lot theory so far. The previous section was meant to give you an understanding of some useful concepts of electronics. There can be numerous components, including ICs and digital sensors, as peripherals of a microprocessor. There can be a large amount of data with the peripheral devices, and there might be a need to send it to the processor. How do they communicate? How does the processor understand that the data is coming into it and that it is being sent by the sensor? There is a serial, or parallel, data-line connection between ICs and a microprocessor. Parallel connections are faster than the serial one but are less preferred because they require more lines, for example, 8, 16, or more than that. A PCI bus can be an example of a parallel communication. Usually in a complex or high-density circuit, the processor is connected to many peripherals, and in that case, we cannot have that many free pins/lines to connect an additional single IC. Serial communication...