21. TM1637 4-Digit Display

This lesson uses: Arduino UNO R3 board, TinkerBlock TK51 TM1637 4-Digit Display module, jumper wires (or breadboard). Learn library install and use; control the 4-digit display with TM1637Display library; outcome: display counts up from 0 to 9999, changing every 0.5 s, then repeats.

1. Install the library

Before writing code, install the TM1637Display library:

1. Arduino IDE: Tools → Manage Libraries...
2. Search: TM1637Display
3. Find TM1637Display by Avishay Orpaz, click Install
4. Wait until installation finishes

2. Wiring

Connect TK51 TM1637 4-digit display to Arduino:

• GND → Arduino GND
• VCC → Arduino 5V
• CLK → Arduino D2
• DIO → Arduino D3
• NC leave unconnected

3. New sketch

1. Arduino IDE: File → New (or Ctrl/Cmd + N) to create a blank sketch
2. Confirm board and port are selected (same as Lesson 01)
3. Type the code below into the file top and into setup() and loop() yourself

4. Program structure

Same as last lesson: two fixed blocks setup() and loop().

• setup(): Include library, create display object, set brightness; runs once.
• loop(): Keep repeating “show number → wait → show next number → repeat”.

After uploading the display will count from 0 to 9999; two wires drive four digits.

5. Code to write

Type the code below at the top of the file and in setup() and loop() (do not copy-paste; typing it yourself helps you remember):

#include <TM1637Display.h>   // Include library

#define CLK_PIN 2   // CLK on D2
#define DIO_PIN 3   // DIO on D3

// Create display object
TM1637Display display(CLK_PIN, DIO_PIN);

void setup() {
  display.setBrightness(7);   // Brightness 0-7, 7 = brightest
  Serial.begin(9600);
  Serial.println("4-digit display program started");
}

void loop() {
  // Show 0-9999 in a loop
  for (int i = 0; i < 10000; i++) {
    display.showNumberDec(i);   // Show number i
    Serial.print("Display: ");
    Serial.println(i);
    delay(500);
  }
}

Program notes

Overall idea: TM1637 talks to Arduino on two lines (CLK, DIO); the library handles the protocol. After creating the display object, setBrightness(0–7) sets brightness and showNumberDec(i) shows decimal i. A for loop from 0 to 9999 gives the counting effect.

6. Hands-on

1. After entering the code, click Verify (✓) to compile
2. Click Upload (→) to upload to the board
3. Watch TK51: it should show 0, 1, 2, 3... up to 9999, then repeat
4. Try yourself:
   • Use display.showNumberDec(i, true) to show leading zeros
   • Show a fixed number, e.g. display.showNumberDec(1234)

Expected result: As in the figure.

Proceed to Lesson 22.

7. Common issues

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