I tried using this sample code but it doesn't work. It ignores the data array and just turns on all the LEDS. My set up is one 595 shift register that controls PNP transistors while the Cathodes of the LEDS are tied to the Arduino. I can turn on a row by setting the pinstate to low so that the Arduino sinks current but I can't control single LEDS. Any help?
//Pin connected to latch pin (ST_CP) of 74HC595
const int latchPin = 6;
//Pin connected to clock pin (SH_CP) of 74HC595
const int clockPin = 12;
////Pin connected to Data in (DS) of 74HC595
const int dataPin = 7;
int rowArr[8] = {5,4,3,2,8,9,10,11}; // Pins where each Cathode is connected
byte data;
byte dataArray[8];
void setup() {
//set pins to output because they are addressed in the main loop
pinMode(latchPin, OUTPUT);
Serial.begin(9600);
pinMode(5,OUTPUT);
pinMode(4,OUTPUT);
pinMode(3,OUTPUT);
pinMode(2,OUTPUT);
pinMode(8,OUTPUT);
pinMode(9,OUTPUT);
pinMode(10,OUTPUT);
pinMode(11,OUTPUT);
//Binary notation as comment
dataArray[0] = 0xFF;
dataArray[1] = 0xFE;
dataArray[2] = 0xFE;
dataArray[3] = 0xFE;
dataArray[4] = 0xFE;
dataArray[5] = 0xFF;
dataArray[6] = 0xFF;
dataArray[7] = 0xFE;
digitalWrite(5,HIGH);
digitalWrite(4,HIGH);
digitalWrite(3,HIGH);
digitalWrite(2,HIGH);
digitalWrite(8,HIGH);
digitalWrite(9,HIGH);
digitalWrite(10,HIGH);
digitalWrite(11,HIGH);
}
void loop() {
for (int j = 0; j < 8; j++) {
//load the light sequence you want from array
data = dataArray[j];
//ground latchPin and hold low for as long as you are transmitting
digitalWrite(latchPin, 0);
//move 'em out
shiftOut(dataPin, clockPin, data);
//return the latch pin high to signal chip that it
//no longer needs to listen for information
digitalWrite(latchPin, 1);
digitalWrite(rowArr[j],LOW);
delay(25);
digitalWrite(rowArr[j],HIGH);
}
}
// the heart of the program
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;
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;
digitalWrite(rowArr[i],HIGH);
}
//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);
}
//blinks the whole register based on the number of times you want to
//blink "n" and the pause between them "d"
//starts with a moment of darkness to make sure the first blink
//has its full visual effect.
! However, some LEDs are dimly lit even though they aren't supposed to. Hardware or software issue?