LED Pattern Controller

Interactive LED animation controller for Arduino using the 74HC595 shift register. The project demonstrates multiple LED animation modes with switching via a push button.

Features

• 6 display modes
• Button-controlled mode switching
• 74HC595 shift register support
• Clean and modular code structure
• Easy to extend with new animation patterns

Hardware

• Arduino Uno (or compatible)
• 74HC595 Shift Register
• 8 LEDs
• 8 * 220 Ω resistors
• Push button
• Breadboard
• Jumper wires

Wiring

Arduino	74HC595
D8	ST_CP (Latch)
D12	SH_CP (Clock)
D11	DS (Data)
GND	GND
5V	VCC

Button connection:

Arduino	Button
D2	Button
GND	Button

The button uses the internal pull-up resistor (INPUT_PULLUP).

Pin Description

Arduino Pin	Type	Connected Device	Description
D8	Output	ST_CP (Latch)	Latches the shifted data and updates the outputs of the 74HC595.
D12	Output	SH_CP (Clock)	Clock signal used to shift bits into the register.
D11	Output	DS (Data)	Serial data input for the 74HC595.
D2	Input (INPUT_PULLUP)	Push Button	Changes the current LED animation mode when pressed.
5V	Power	74HC595 VCC	Supplies power to the shift register.
GND	Ground	74HC595 GND, Button	Common ground for the circuit.

74HC595 Output Mapping

Output Pin	LED
Q0	LED 1
Q1	LED 2
Q2	LED 3
Q3	LED 4
Q4	LED 5
Q5	LED 6
Q6	LED 7
Q7	LED 8

Display Modes

Mode	Description
0	All LEDs ON
1	Running light (Left -> Right)
2	Running light (Right -> Left)
3	Center -> Edges animation
4	Edges -> Center animation
5	Even/Odd LEDs blinking

Pin Configuration

const int latchPin = 8;
const int clockPin = 12;
const int dataPin = 11;
const int buttonPin = 2;

How It Works

The Arduino sends an 8-bit value to the 74HC595 using the shiftOut() function. Each bit represents the state of one LED.

The push button changes the current animation mode. Each mode continuously displays its pattern until another button press is detected.

Example Patterns

Pattern	Binary
All ON	11111111
Even LEDs	10101010
Odd LEDs	01010101
Center	00011000
Edges	10000001