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.
Digital pins can normally only output HIGH or LOW. Using the Arduino UNO R4’s fast clock, we drive all 20 pins with Software PWM to render three different waves of light — complete with gamma correction and full source code.
Build a playable electronic piano with an Arduino UNO R4 and a passive piezo buzzer. Complete with a note-to-frequency table, circuit diagram, annotated code, demo videos, and an FAQ covering the usual pitfalls — finished in about an hour.