# Lesson 20: Using TM1637 4 digit display

Please select other codes for this lecture from the links below.

Related or required files and link to this lesson

### Part 2: LCD, LED and OLED Screens

In this lecture we learn how to use TM1637 four digit seven segment display to display integer and hexadecimal vlaues. Decimal point can't be dispalyed easily.

``````
/*
*  Robojax Arduino Step By Step Course
* Lesson 20-1  Introduction to TM1637 4 digits LED Display
*
*  This code has been modefied from the Arduino library

Please watch video instruction here https://youtu.be/cJqmXjERwkQ
This code is available at http://robojax.com/course1/?vid=lecture11

with over 100 lectures Free On  YouTube Watch it here http://robojax.com/L/?id=338
Get the code for the course: http://robojax.com/L/?id=339
*  Updted by Ahmad Shamshiri for Robojax
*  in Ajax, Ontario, Canada
*
*
*  This is code for LCD1602 Display with I2C module
*  which can display text on the screen.
*/
#include <Arduino.h>
#include <TM1637Display.h>

// Module connection pins (Digital Pins)
#define CLK 5
#define DIO 6

// The amount of time (in milliseconds) between tests
#define TEST_DELAY   2000

const uint8_t SEG_DONE[] = {
SEG_B | SEG_C | SEG_D | SEG_E | SEG_G,           // d
SEG_A | SEG_B | SEG_C | SEG_D | SEG_E | SEG_F,   // O
SEG_C | SEG_E | SEG_G,                           // n
SEG_A | SEG_D | SEG_E | SEG_F | SEG_G            // E
};

TM1637Display display(CLK, DIO);

void setup()
{
//Robojax Arduino Step By Step Course http://robojax.com/L/?id=338
}

void loop()
{
//Robojax Arduino Step By Step Course http://robojax.com/L/?id=338
int k;
uint8_t data[] = { 0xff, 0xff, 0xff, 0xff };
display.setBrightness(0x0f);

// All segments on
display.setSegments(data);
delay(TEST_DELAY);

// Selectively set different digits
data[0] = 0b01001001;
data[1] = display.encodeDigit(1);
data[2] = display.encodeDigit(2);
data[3] = display.encodeDigit(3);

for(k = 3; k >= 0; k--) {
display.setSegments(data, 1, k);
delay(TEST_DELAY);
}

display.setSegments(data+2, 2, 2);
delay(TEST_DELAY);

display.setSegments(data+2, 2, 1);
delay(TEST_DELAY);

display.setSegments(data+1, 3, 1);
delay(TEST_DELAY);

// Show decimal numbers with/without leading zeros
bool lz = false;
for (uint8_t z = 0; z < 2; z++) {
for(k = 0; k < 10000; k += k*4 + 7) {
display.showNumberDec(k, lz);
delay(TEST_DELAY);
}
lz = true;
}

// Show decimal number whose length is smaller than 4
for(k = 0; k < 4; k++)
data[k] = 0;
display.setSegments(data);

// Run through all the dots
for(k=0; k <= 4; k++) {
display.showNumberDecEx(0, (0x80 >> k), true);
delay(TEST_DELAY);
}

display.showNumberDec(153, false, 3, 1);
delay(TEST_DELAY);
display.showNumberDec(22, false, 2, 2);
delay(TEST_DELAY);
display.showNumberDec(0, true, 1, 3);
delay(TEST_DELAY);
display.showNumberDec(0, true, 1, 2);
delay(TEST_DELAY);
display.showNumberDec(0, true, 1, 1);
delay(TEST_DELAY);
display.showNumberDec(0, true, 1, 0);
delay(TEST_DELAY);

// Brightness Test
for(k = 0; k < 4; k++)
data[k] = 0xff;
for(k = 0; k < 7; k++) {
display.setBrightness(k);
display.setSegments(data);
delay(TEST_DELAY);
}

// On/Off test
for(k = 0; k < 4; k++) {
display.setBrightness(7, false);  // Turn off
display.setSegments(data);
delay(TEST_DELAY);
display.setBrightness(7, true); // Turn on
display.setSegments(data);
delay(TEST_DELAY);
}

// Done!
display.setSegments(SEG_DONE);

while(1);

//Robojax Arduino Step By Step Course http://robojax.com/L/?id=338
}

```  ```

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