SPI

A side-by-side comparison of the three serial buses every microcontroller project runs into — I2C, SPI and UART — across four axes: number of signal lines, speed, how many devices you can hang off them, and wiring distance. Includes a decision flow and what to look for on a scope.

A thorough guide to using the 74HC595 with Arduino. Expand your GPIO without limit using just three signal lines — from shiftOut() to hardware SPI, with schematics, KiCad design files, and sample code. Fully compatible with the Arduino UNO R4.