SPI Protocol Support

SPI (Serial Peripheral Interface) is a synchronous serial communication protocol widely used for high-speed, short-distance communication between microcontrollers and peripheral devices. Developed by Motorola, SPI uses a master-slave architecture with four primary signals: SCLK (Serial Clock), MOSI (Master Out Slave In), MISO (Master In Slave Out), and CS/SS (Chip Select/Slave Select). Unlike I2C, SPI operates in full-duplex mode, allowing simultaneous data transmission and reception. SPI is the preferred interface for NOR flash memory, SD cards, display controllers, ADCs, DACs, and high-speed sensors due to its simplicity and ability to achieve clock rates exceeding 50 MHz. The protocol has no formal specification, which means implementations vary — engineers must pay attention to clock polarity (CPOL), clock phase (CPHA), bit order, and word size for each device. Common SPI modes (0 through 3) define different combinations of CPOL and CPHA. Protocol analysis is critical for SPI debugging because the lack of standardized framing and acknowledgment makes it difficult to diagnose issues from signal waveforms alone. A protocol analyzer decodes the raw signals into readable command and data bytes, helping engineers verify flash memory read/write operations, sensor register configurations, and data integrity across the bus.