2 Digit Numbers on a Double 7 Segment Display

Projects Programming
1

I've been making a timer using a double 7 segment. I am trying to run a countdown from 20 to 0. In my code below, the letters (a, b, c, d, e, f, g, and h) represent the segments. What I want is for 2 sections of my code below (Section One & Section Two) to run at once, so that I can display double digit numbers. I am not sure how to do it and I would appreciate it if someone could give me a solution.

void Twenty() {

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  digitalWrite(commonOne, LOW);     //Section One
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, LOW);
  digitalWrite(d, HIGH);
  digitalWrite(e, HIGH);
  digitalWrite(f, LOW);
  digitalWrite(g, HIGH);
  digitalWrite(h, LOW);
  delay(1000);
  digitalWrite(commonOne, HIGH);
----------------------------------------------
  digitalWrite(commonTwo, LOW);     //Section Two
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, HIGH);
  digitalWrite(e, HIGH);
  digitalWrite(f, HIGH);
  digitalWrite(g, LOW);
  digitalWrite(h, LOW);
  delay(1000);
  digitalWrite(commonTwo, HIGH);
----------------------------------------------
2

Rasbir16:
That's what I don't want to do. I have already considered that but I want a solution so I can use a DOUBLE 7 segment display rather than a SINGLE 7 segment display.

Oops, I suggested a Mega and then deleted my post. Sorry, I hardly ever get beaten to an answer before it's gone. My bad. In that case, you just need to shorten the delay so the display can alternate digits faster than the eye can see.

For example, delay(5);

3

Your code shows how you might start to display the number 20 on your display, but you have also 19 more numbers to display so the program could get long if you do it in that way.

One suggestion is to write a general function, say : void displayDigit( byte displaySide, byte digit ) that displays a selected digit on the selected side of the display, leaving the other side of the display still showing its number.

Since your display (probably) has a common element (cathode or anode) you have to switch quickly between the left and the right side of the display to give the visual impression that both sides are simultaneously showing their respective digits (multiplexing).

Then, in the loop , you step down from 20 to 0, an in each interval between one number and the next, you continually alternate between the display of the left and right digits.

4

Thank you. I will code my program to multiplex.