hey guy/girls,
i was wondering if you could please help me alter this code so that i can fade 24 leds. i want the device they go into to look as though it is breathing, through light. so i would like the leds to fade up to 255 in about 1000ms and then fade down to 0 in say 2000ms.
a am using an arduino duemilanove and 3 74hc595 shift registers.
this is the code so far.
//Pin connected to ST_CP of 74HC595
int latchPin = 6;
//Pin connected to SH_CP of 74HC595
int clockPin = 4;
////Pin connected to DS of 74HC595
int dataPin = 5;
void setup() {
pinMode(latchPin, OUTPUT);
Serial.begin(9600);
}
void loop() {
int z=0;
for (z=0; z<=255; z++) {
digitalWrite(latchPin, 0); // ground the latchpin
shiftOut(dataPin, clockPin, z);
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, 0);
digitalWrite(latchPin, 1); // return the latch pin high
digitalWrite(latchPin, 0); // ground the latchpin
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, z);
shiftOut(dataPin, clockPin, 0);
// 2nd register ignite all 8 LEDs
digitalWrite(latchPin, 1); // return the latch pin high
digitalWrite(latchPin, 0); // ground the latchpin
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, z);
digitalWrite(latchPin, 1); // return the latch pin 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;
}
//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);
}
clearly you can see i have altered it from the shiftout tutorial on the arduino site and also added what another poster has done which is to shift out so that only 8 leds are on at a time but through POV you see them all on. i then wrote a loop so that what they shifted out goes from 0 to 255 but this is wrong for what i want to do because this actually just shifts out a count, which is not what i want.
i know i need to write some math that shifts out so that all the leds turn on for the full time and then turn on and then off for progressively longer times until they are all off and then do the oppersite for fading them back up. basically alter the duty cycle of three bytes.
but the problem is im not sure how to go about writing this.
if anyone could help or point me in the right direction i would be very greatful.
cheers,
sebastian.