74HC595

Description

The 74HC595 is an 8-bit Serial-In, Parallel-Out (SIPO) Shift Register. It is most famous for “expanding” the output pins of a microcontroller. With just 3 pins from your Arduino or ESP32, you can control 8 separate output channels—and you can even daisy-chain multiple 595s together to control dozens of outputs using those same 3 pins.

How It Works

It uses a “bucket brigade” system for data:

1. Shift Register: Data is “clocked in” bit-by-bit (0s and 1s).

2. Storage Register (Latch): Once all 8 bits are inside, you “latch” the data to the output pins all at once. This prevents the outputs from flickering while the data is moving.

3. Output Enable: A dedicated pin can turn all outputs on or off instantly without losing the stored data.