This code is straight c/p from the tutorial, except that I've added 2 more lines since I'm using 4 instead of 2 shift registers and there's my own array.
Notice: I only have LEDs on 1st and 2nd shift register at the moment. 8 on the first and 5 on 2nd.
//**************************************************************//
// Name : shiftOutCode, Dual Binary Counters //
// Author : Carlyn Maw, Tom Igoe //
// Date : 25 Oct, 2006 //
// Version : 1.0 //
// Notes : Code for using a 74HC595 Shift Register //
// : to count from 0 to 255 //
//**************************************************************//
//Pin connected to ST_CP of 74HC595
int latchPin = 3;
//Pin connected to SH_CP of 74HC595
int clockPin = 4;
////Pin connected to DS of 74HC595
int dataPin = 2;
int array[] = {1,2,4,8,16,32,64,128,255};
void setup() {
//Start Serial for debuging purposes
Serial.begin(9600);
//set pins to output because they are addressed in the main loop
pinMode(latchPin, OUTPUT);
}
void loop() {
//count up routine
for (int j = 0; j < 9; j++) {
//ground latchPin and hold low for as long as you are transmitting
digitalWrite(latchPin, 0);
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, array[j]);
shiftOut(dataPin, clockPin, array[j]);
//return the latch pin high to signal chip that it
//no longer needs to listen for information
digitalWrite(latchPin, 1);
delay(1000);
}
}
void shiftOut(int myDataPin, int myClockPin, byte myDataOut) {
// This shifts 8 bits out MSB first,
//on the rising edge of the clock,
//clock idles low
//internal function setup
int i=0;
s int pinState;
pinMode(myClockPin, OUTPUT);
pinMode(myDataPin, OUTPUT);
//clear everything out just in case to
//prepare shift register for bit shifting
digitalWrite(myDataPin, 0);
digitalWrite(myClockPin, 0);
//for each bit in the byte myDataOut?
//NOTICE THAT WE ARE COUNTING DOWN in our for loop
//This means that %00000001 or "1" will go through such
//that it will be pin Q0 that lights.
for (i=7; i>=0; i--) {
digitalWrite(myClockPin, 0);
//if the value passed to myDataOut and a bitmask result
// true then... so if we are at i=6 and our value is
// %11010100 it would the code compares it to %01000000
// and proceeds to set pinState to 1.
if ( myDataOut & (1<<i) ) {
pinState= 1;
}
else {
pinState= 0;
}
//Sets the pin to HIGH or LOW depending on pinState
digitalWrite(myDataPin, pinState);
//register shifts bits on upstroke of clock pin
digitalWrite(myClockPin, 1);
//zero the data pin after shift to prevent bleed through
digitalWrite(myDataPin, 0);
}
//stop shifting
digitalWrite(myClockPin, 0);
}
Now, if I write this:
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, array[j]);
First shift register (the one which has clock pin, latch and data pin connected to Arduino) works perfectly. All 8 LEDs turn on as expected EXCEPT for this:
array[7] - last LED on first SR turns on
array[8] (255) - every LED on first SR turns on
array[0] (again) - every LED on both SR turns on
array[1] - second LED on first SR turns on
then it works all fine until array[0] comes again.
Notice: when I upload the sketch and the loop starts, array[0] turns only first LED on first SR until the loop starts again, then array[0] turns on every LED on both SR.
If I write this code
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, array[j]);
shiftOut(dataPin, clockPin, 0);
LEDs on 2nd SR turn on and off repeatedly (not one by one but all).
I'm running out of ideas here.