Go Down

Topic: shift registers and row of leds (Read 899 times) previous topic - next topic


Hi... I chained 2 shift registers with a bank of leds to attached each and successfully had them light up one at a time. Great.

Now I want to scale up.

I added another shift register and 8 more leds...

I have not been able to modify the following program (which I got off the internet and modified) to correctly light up the leds from 0 to 24 or 32 or 40... I want to understand how to modify the program so that I can chain any number of shift registers and be able to light up the full string or any individual led...

I would very much appreciate the help!!!!

Here it is:

// chain multiple shift registers, each with 8 leds
// light 1 led at a time, from 1 to 24 - blanking out each previous lit led
// then start again
//Pin connected to ST_CP of 74HC595
int latchPin = 8;
//Pin connected to SH_CP of 74HC595
int clockPin = 12;
////Pin connected to DS of 74HC595
int dataPin = 11;

void setup() {
pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
digitalWrite(latchPin, 0); //make sure data isn't latched
void loop() {
unsigned int outputpattern =1; //stores the output pattern as an unsigned int, that is, two bytes
int pattern_LSB; //the least significant byte (LSB) of the pattern
int pattern_MSB; //the most significant byte (MSB) of the pattern
for (int i=0 ; i< 16; i++){
pattern_MSB = outputpattern >>8; //extract the MSB of the pattern by shifting all the bits over by 8
pattern_LSB = outputpattern & B11111111; //extract the LSB of the pattern by bitwise AND
shiftOut(dataPin, clockPin, MSBFIRST, (byte) pattern_MSB);
shiftOut(dataPin, clockPin, MSBFIRST, (byte) pattern_LSB);
digitalWrite(latchPin, 1); // flick the latch to put the data on the output pins

digitalWrite(latchPin, 0);

outputpattern = outputpattern <<1; // shift the outputpattern left by one bit



Oct 23, 2009, 03:36 am Last Edit: Oct 23, 2009, 12:12 pm by pwillard Reason: 1


You got your question asked and answered in a different forum...

Go Up

Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

via Egeo 16
Torino, 10131