SPI tutorials & labs.

The most complete SPI curriculum on the internet — from first principles (why SPI, synchronous serial, the full-duplex shift-register model) through signals, bus architecture, clocking, the four CPOL/CPHA modes, framing, read/write/multi-byte transfers, chip-select management, flash and sensor access, Dual/Quad/Octal SPI and XIP, performance, RTL design, verification, debugging, and interview mastery.