Hi
I have been experimenting with the starter program – 8 more LED's. I added in a total of 12 LED's using the same basic circuit layout – I added in 4 extra LED's using pins 5, 6, 7, 8. I then used the chip 74HC595 for - pin 2 – 14-Data, pin 4 – 12 – Latch and pin 3 – 11- CIK.
I am a little stuck on the program – the only lights that I can get to light up is the LED's connected straight to pins 5, 6, 7, 8. I am trying to adapt the original program see below:
Any ideas?
Thanks
Paul
/* ---------------------------------------------------------
* | Arduino Experimentation Kit Example Code |
* | CIRC-05 .: 8 More LEDs :. (74HC595 Shift Register) |
* ---------------------------------------------------------
*
* We have already controlled 8 LEDs however this does it in a slightly
* different manner. Rather than using 8 pins we will use just three
* and an additional chip.
*
* For more information on this circuit http://tinyurl.com/111111/
*
*/
//Pin Definitions
//The 74HC595 using a protocol called SPI (for more details http://www.arduino.cc/en/Tutorial/ShiftOut)
//Which has three pins
int data = 2;
int clock = 3;
int latch = 4;
//Used for single LED manipulation
int ledState = 0;
const int ON = HIGH;
const int OFF = LOW;
/*
* setup() - this function runs once when you turn your Arduino on
* We set the three control pins to outputs
*/
void setup()
{
pinMode(data, OUTPUT);
pinMode(clock, OUTPUT);
pinMode(latch, OUTPUT);
}
/*
* loop() - this function will start after setup finishes and then repeat
* we set which LEDs we want on then call a routine which sends the states to the 74HC595
*/
void loop() // run over and over again
{
int delayTime = 100; //the number of milliseconds to delay between LED updates
for(int i = 0; i < 256; i++){
updateLEDs(i);
delay(delayTime);
}
}
/*
* updateLEDs() - sends the LED states set in ledStates to the 74HC595
* sequence
*/
void updateLEDs(int value){
digitalWrite(latch, LOW); //Pulls the chips latch low
shiftOut(data, clock, MSBFIRST, value); //Shifts out the 8 bits to the shift register
digitalWrite(latch, HIGH); //Pulls the latch high displaying the data
}
/*
* updateLEDsLong() - sends the LED states set in ledStates to the 74HC595
* sequence. Same as updateLEDs except the shifting out is done in software
* so you can see what is happening.
*/
void updateLEDsLong(int value){
digitalWrite(latch, LOW); //Pulls the chips latch low
for(int i = 0; i < 8; i++){ //Will repeat 8 times (once for each bit)
int bit = value & B10000000; //We use a "bitmask" to select only the eighth
//bit in our number (the one we are addressing this time through
value = value << 1; //we move our number up one bit value so next time bit 7 will be
//bit 8 and we will do our math on it
if(bit == 128){digitalWrite(data, HIGH);} //if bit 8 is set then set our data pin high
else{digitalWrite(data, LOW);} //if bit 8 is unset then set the data pin low
digitalWrite(clock, HIGH); //the next three lines pulse the clock pin
delay(1);
digitalWrite(clock, LOW);
}
digitalWrite(latch, HIGH); //pulls the latch high shifting our data into being displayed
}
//These are used in the bitwise math that we use to change individual LEDs
//For more details http://en.wikipedia.org/wiki/Bitwise_operation
int bits[] = {B00000001, B00000010, B00000100, B00001000, B00010000, B00100000, B01000000, B10000000};
int masks[] = {B11111110, B11111101, B11111011, B11110111, B11101111, B11011111, B10111111, B01111111};
/*
* changeLED(int led, int state) - changes an individual LED
* LEDs are 0 to 7 and state is either 0 - OFF or 1 - ON
*/
void changeLED(int led, int state){
ledState = ledState & masks[led]; //clears ledState of the bit we are addressing
if(state == ON){ledState = ledState | bits[led];} //if the bit is on we will add it to ledState
updateLEDs(ledState); //send the new LED state to the shift register
}
