Basic microcontroller interview questions, don't miss this one. When it comes to microcontrollers, one of the essential components is the Serial Peripheral Interface (SPI). This full-duplex synchronous serial communication interface is used for short-distance communications within a single device. But that’s just scratching the surface of what SPI can do.  The SPI interface uses four signal lines for data transmission and reception. These include two data lines (MISO, Master In Slave Out, and MOSI, Master Out Slave In), one clock line, and one select chip line. The controller acts as the master device, while any slave devices connected to it act as slaves. This means that all communication takes place between the controller and the slave devices only after they are selected by the controller.   In an SPI system, when you want to transfer data from a master device to a slave device or vice versa, first, you must select a particular slave device using its chip select line. Then you need to provide commands using two data lines—the MOSI and MISO lines—and then clock them in with a clock line. The clock pulses allow synchronization between communicating parties which helps in the proper timing of the data transmission process. In an SPI system, when you want to transfer data from a master device to a slave device or vice versa, first you must select a particular slave device using its chip select line. Then you need to provide commands using two data lines—the MOSI and MISO lines—and then clock them in with a clock line. The clock pulses allow synchronization between communicating parties which helps in proper timing of data transmission process.