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Serial Peripheral Interface – SPI Bus overview

Serial Peripheral Interface is a simple interface that enables communicating microcontroller and peripheral chips or intercommunicating 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 the synchronous protocol, where transmitting and receiving is guided by a clock signal generated by the 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). The master generates a MOSI signal – the recipient is Slave. MOSI may also be labeled as SI or SDI. Slaves generate MISO signals. 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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