Example usage for StuffAndyMakes.com Simple LED Controller shift register breakout board

SimpleLEDController.cpp

#include "Arduino.h"

#define data 8
#define clk 9
#define oe 7
#define rst 6

void pulseClock() {
    digitalWrite(clk, HIGH);
    digitalWrite(clk, LOW);
}

void setLEDs(uint8_t leds) {
    // reset chip
    digitalWrite(rst, LOW);
    digitalWrite(rst, HIGH);
    // if set to 0, just bombo out, since all LEDs are off at this point
    if (leds == 0) return;
    // turn off display (active low)
    digitalWrite(oe, HIGH);
    // shift in bits
    for (uint8_t bit = 0; bit < 8; bit++) {
        digitalWrite(data, (leds & (1 << bit)) == (1 << bit) ? HIGH : LOW);
        pulseClock();
    }
    pulseClock();
    // turn on display (active low)
    digitalWrite(oe, LOW);
}

void setup() {
    pinMode(data, OUTPUT);
    pinMode(clk, OUTPUT);
    pinMode(oe, OUTPUT);
    pinMode(rst, OUTPUT);
}

void loop() {
    uint8_t a = 0;
    while (a != 255) {
        a = (a << 1) + 1;
        setLEDs(a);
        delay(100);
    }
    while (a != 0) {
        a = (a << 1);
        setLEDs(a);
        delay(100);
    };
}