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/*
Shift Register Example
for two 74HC595 shift registers
This sketch turns on each of the LEDs attached to two 74HC595 shift registers,
in sequence from output 0 to output 15.
Hardware:
* 2 74HC595 shift register attached to pins 2, 3, and 4 of the Arduino,
as detailed below.
* LEDs attached to each of the outputs of the shift register
Created 22 May 2009
Modified 23 Mar 2010
by Tom Igoe
*/
//Pin connected to latch pin (ST_CP) of 74HC595
const int latchPin = 8;
//Pin connected to clock pin (SH_CP) of 74HC595
const int clockPin = 12;
////Pin connected to Data in (DS) of 74HC595
const int dataPin = 11;
char inputString[2];
void setup() {
//set pins to output because they are addressed in the main loop
pinMode(latchPin, OUTPUT);
pinMode(dataPin, OUTPUT);
pinMode(clockPin, OUTPUT);
Serial.begin(9600);
Serial.println("reset");
}
void loop() {
// iterate over the 16 outputs of the two shift registers
for (int thisLed = 0; thisLed < 16; thisLed++) {
// write data to the shift registers:
registerWrite(thisLed, HIGH);
// if this is not the first LED, turn off the previous LED:
if (thisLed > 0) {
registerWrite(thisLed - 1, LOW);
}
// if this is the first LED, turn off the highest LED:
else {
registerWrite(15, LOW);
}
// pause between LEDs:
delay(250);
}
}
// This method sends bits to the shift registers:
void registerWrite(int whichPin, int whichState) {
// the bits you want to send. Use an unsigned int,
// so you can use all 16 bits:
unsigned int bitsToSend = 0;
// turn off the output so the pins don't light up
// while you're shifting bits:
digitalWrite(latchPin, LOW);
// turn on the next highest bit in bitsToSend:
bitWrite(bitsToSend, whichPin, whichState);
// break the bits into two bytes, one for
// the first register and one for the second:
byte registerOne = highByte(bitsToSend);
byte registerTwo = lowByte(bitsToSend);
// shift the bytes out:
shiftOut(dataPin, clockPin, MSBFIRST, registerTwo);
shiftOut(dataPin, clockPin, MSBFIRST, registerOne);
// turn on the output so the LEDs can light up:
digitalWrite(latchPin, HIGH);
}