How to light up the two points that is in the middle? It only lights up when the digB is set to LOW, and it lights up all 3 points that is in the middle.


Example code:

const int displayPins[] = {2,3,4,5,6,7,8,9,10,11,12,13};
const int digA = 7;
const int digB = 4;
const int digC = 3;
const int digD = 8;
const int decimalPoint = 10;

void setup() {
    for (int i = 0; i < (sizeof(displayPins)/sizeof(displayPins[0])); i++) {
        pinMode(displayPins[i], OUTPUT);

    digitalWrite(digA, 1);
    digitalWrite(digB, 0);
    digitalWrite(decimalPoint, 1);
    digitalWrite(digC, 1);
    digitalWrite(digD, 1);

void loop() {

I want to display a clock in this format: 00:00. But did not found a way to light up the two points that is in the middle.

  • refer to the datasheet
    – jsotola
    Sep 10 at 0:40
  • @jsotola Did not found the right one, all that i found is the display with 4 digits and decimals without the two points in the middle. I also searched for the model of the item "sh5463AS-34", but did not found anything.
    – mario
    Sep 10 at 2:09
  • 1
    there are several schematics on the web ... the part number to search is in the picture you posted ... your question is not arduino specific ... voting to close
    – jsotola
    Sep 10 at 3:00
  • 1
    The schematic on this site shows, that the three dots are all connected together, thus can only light up together. Seems to be the model, that you have. In that case you cannot do anything about that, other than buying a different 7segment display.
    – chrisl
    Sep 10 at 6:03
  • 1
    @chrisl i somehow missed the part about the three leds lighting ... have not had my morning coffee yet ... my thought was that reversing the polarity would light the colon leds ... looks like the display requires black tape for selecting the display mode
    – jsotola
    Sep 10 at 6:52

It is not possible to separate the colon dots from the decimal point dot - they are all wired together in parallel internally:

enter image description here

As has been mentioned in the comments you need to use the "black tape" method of selecting the LEDs. That's not a joke, that's really what's done. Cover the LED that you don't want visible with black tape (or black paint, etc).

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