Serial Peripheral Interface – SPI Bus overview

Serial Peripheral Interface is a simple interface which enables to communicate microcontroller and peripheral chips or intercommunicate between two or more microcontrollers. Serial Peripheral Interface bus sometimes called four wire interface may be used to interface such chips or devices like: LCD, sensors, memories, ADC, RTC. The range of usage is huge. SPI Bus uses synchronous protocol, where transmitting and receiving is guided by clock signal generated by master microcontroller. SPI interface allows connecting several SPI devices while master selects each of them with CS (Chip Select) signal – (Underline means that active is LOW). SPI bus consists of four signal wires: Master Out Slave In (MOSI), Master In Slave Out (MISO), Serial Clock (SCLK or SCK) Chip Select (CS) for the peripheral. Some microcontrollers have a dedicated chip select for SPI interfacing called Slave Select (SS). MOSI signal is generated by master – recipient is Slave. MOSI may also be labeled as SI or SDI. MISO signals are generated by slave. In some chips you might find labels SO or SDO. SCLK or SCK are generated by master to synchronize data transfers. CS (SS) signal is also generated by master to select slave chip or device. Data transfer is…

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