Can't get 4 digit 7 segment display to show different values I'm an Arduino newbie having problems getting a 4 digit 7 segment display to work. The display is connected to a 74HC595 and the setup is from the elegoo tutorial 28 (I think it is download only).

I figured how to control which number to display, but all 4 digits always share the same number, so it is always like 1111, 5555, 9999 etc.

I've heard about something called multiplexing which might do the trick, but I can't adapt it to my project yet, missing too much experience.

This is the code that toggles between 2222 and 8888.
I want to be able to display any number like 1234 though.

Any help is very appreciated.

int latch=9;  //74HC595  pin 9 STCP
int clock=10; //74HC595  pin 10 SHCP
int data=8;   //74HC595  pin 8 DS

void setup()
{
  pinMode(latch,OUTPUT);
  pinMode(clock,OUTPUT);
  pinMode(data,OUTPUT);
}

void Display(unsigned int num)
{  
  digitalWrite(latch,LOW);
  shiftOut(data,clock,MSBFIRST,num);
  digitalWrite(latch,HIGH); 
}

void loop()
{
    Display(91);
    delay(1000);
    Display(127);
    delay(1000);
}
You have a common cathode display and all your cathodes are tied to ground through resistors. You have no way at all of separating out the different digits.

You cannot directly drive such a display with a shift register like that - you need a more direct connection to the Arduino (it needs to be high speed) and rapidly switch each cathode on and off in sequence to display each of the four numbers one after another.

Also the resistors should be in the 8 anodes, not the 4 cathodes.