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Topic: How to show the two dots on 4 digit 7 segments display (Read 99 times) previous topic - next topic


For a project I want to make a countdown timer with a 4 digit 7 segments display, so I found this tutorial on Youtube. The timer is working, but the two colon dots aren't working. Anyone who knows how to fix this?

#include <Arduino.h>
#include <TM1637Display.h>

#define CLK 2
#define DIO 3

#define numberOfSeconds(_time_) ((_time_ / 1000) %60)
#define numberOfMinutes(_time_) (((_time_ / 1000) / 60) % 60)

TM1637Display display(CLK, DIO);

const uint8_t OFF[] = {0, 0, 0, 0};
const uint8_t PLAY[] = {B01110011, B00111000, B01011111, B01101110};

// 1000ms in 1sec, 60secs in 1 min, 60mins in 1hr. So, 1000x60x60 = 3600000ms = 1hr
unsigned long timeLimit = 1800000;

void setup() {

void loop() {

void displayText() {

void countdown() {
  unsigned long timeRemaining = timeLimit - millis();

  while (timeRemaining > 0) {
    int seconds = numberOfSeconds(timeRemaining);
    int minutes = numberOfMinutes(timeRemaining);

    display.showNumberDecEx(seconds, 0, true, 2, 2);
    display.showNumberDecEx(minutes, 0x80 >> 3, true, 2, 0);

    timeRemaining = timeLimit - millis();

Everywhere on the internet I read that these lines of code can fix it:

uint8_t segto;
int value = 1244;
segto = 0x80 | display.encodeDigit((value / 100)%10);
display.setSegments(&segto, 1, 1);

But I really don't know what to do with it and how that code works...

Who can help me?

I'm using this display from Aliexpress: https://www.aliexpress.com/item/Free-shipping-4-digital-display-with-adjustable-brightness-LED-module-clock-Point-Accessories-Blocks-for-arduino/1961805015.html?spm=a2g0s.9042311.0.0.3da24c4dj4MuW5


From the TM1637Display.h file showing the syntax for the showNumberDecEx function.

Code: [Select]
@param num The number to be shown
  //! @param dots Dot/Colon enable. The argument is a bitmask, with each bit corresponding to a dot
  //!        between the digits (or colon mark, as implemented by each module). i.e.
  //!        For displays with dots between each digit:
  //!        * 0.000 (0b10000000)
  //!        * 00.00 (0b01000000)
  //!        * 000.0 (0b00100000)
  //!        * (0b11100000)
  //!        For displays with just a colon:
  //!        * 00:00 (0b01000000)
  //!        For displays with dots and colons colon:
  //!        * 0.0:0.0 (0b11100000)
  //! @param leading_zero When true, leading zeros are displayed. Otherwise unnecessary digits are
  //!        blank. NOTE: leading zero is not supported with negative numbers.
  //! @param length The number of digits to set. The user must ensure that the number to be shown
  //!        fits to the number of digits requested (for example, if two digits are to be displayed,
  //!        the number must be between 0 to 99)
  //! @param pos The position of the most significant digit (0 - leftmost, 3 - rightmost)
void showNumberDecEx(int num, uint8_t dots = 0, bool leading_zero = false, uint8_t length = 4, uint8_t pos = 0);

I think that a value of 0x40 in the dots parameter will turn the colon on.

Read the how to use this forum-please read sticky to see how to post code.


Thanks a lot, it works!

I indeed need to change the 0x80 >> 3 to 0x40

Code: [Select]
display.showNumberDecEx(seconds, 0, true, 2, 2);
display.showNumberDecEx(minutes, 0x40, true, 2, 0);

PS. Sorry for not showing the code correctly :smiley-red:


PS. Sorry for not showing the code correctly :smiley-red:
OK, you figured it out now, so go back to the first post and use the "More ==> Modify" option at the bottom right corner to fix that as well.

Note that the TM1637 clock displays have only the colon attached to the third digit IIRC, no decimals.

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