Arduino 74HC595 Shift Register with 8 LEDs
Level 44 · Eight from Three · 30 minutes
Run out of pins? A 74HC595 shift register drives eight LEDs from just three Arduino pins.
Preview the project free; a course seat is required to run and submit. No hardware kit needed.
Your project challenge
Light eight LEDs from three Arduino pins, using a 74HC595 shift register. Show the eight patterns in order, 0.5 second each, and repeat them forever. Data D11, clock D12, latch D8, OE D9. Pull the latch HIGH after every byte, and keep OE LOW.
Components you’ll use
- Arduino Uno
- 74HC595 Shift Register
- LED (Light-Emitting Diode) × 8
What you’ll build
A light show on eight LEDs, using only three Arduino pins.
How it works
- The 74HC595 is a shift register. It turns one wire of bits into eight outputs.
- Put a bit on the data pin,
D11. Pulse the clock pin,D12. The chip takes the bit. shiftOutdoes this eight times for you, one bit per clock pulse.- Then pulse the latch pin,
D8. All eight bits jump onto the LEDs together. - OE on
D9must be LOW, or every LED stays dark.
The key idea
An Uno runs out of pins fast. Three pins can drive eight outputs, and two chips can drive sixteen.
MSBFIRST and LSBFIRST send the bits in opposite orders. Either one works if your patterns match it.
⚠ Watch out
Forget the latch and the bits go into the chip, but nothing lights. Pull it HIGH after every byte.
The interactive editor includes the wiring guide, code editor and simulation controls.