SENSORS/ACTUATORS

INTERNET OF THING (IoT)

ESP32 UNO - TM1637 4-Digit 7-Segment Display

Want a bright number display for your ESP32 Uno? Connect a TM1637 4-digit 7-segment display to the ESP32 Uno form board and print numbers, words and a clock with two wires. The module is a cheap LED display and the DIYables library does the hard work.

By the end, you can:

Wire a TM1637 module to the ESP32 Uno with only CLK and DIO.
Install the DIYables_4Digit7Segment_TM1637 library in Arduino IDE.
Print integers, short text and temperatures with a degree sign.
Show HH:MM time with a blinking colon.
Set single digits and change the brightness.

ESP32 Uno TM1637 4-digit 7-segment display

Components You Need

1	×	ESP32 Uno-form Board
1	×	USB Cable Type-A to Type-C (for USB-A PC)
1	×	USB Cable Type-C to Type-C (for USB-C PC)
1	×	TM1637 4-digit 7-segment Display (colon-separated)
1	×	Jumper Wires

Or you can buy the following kits:

DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .

How the TM1637 Display Works

By the end of this part, you know what the module does and what each pin is for.

The TM1637 chip on the module switches the four digits on and off very fast, so your board does not have to. It keeps the data in its own memory. The digits stay lit while your sketch does other work.

Feature	Value
Digits	4, each with 7 segments and a dot
Colon	1 LED between digit 2 and digit 3
Brightness	8 levels (0 to 7)
Interface	2 wires (CLK and DIO)
Logic and supply	3.3V or 5V

Module Pin	What It Does
CLK	Clock signal from the board
DIO	Data line, both directions
VCC	Power (3.3V or 5V)
GND	Ground

Good to know: any two free GPIO pins can be CLK and DIO. This page uses D9 and D10, the same Uno header positions as the wiring diagram.

ESP32 Uno Pinout

Each Uno header label on the ESP32 Uno form board is tied to one GPIO number, and the sketch uses that number. Look at the picture to see where D9 and D10 sit.

How to Connect

By the end of this part, the display is wired and ready for power.

The wiring diagram between ESP32 Uno TM1637 4-Digit 7-Segment Display

This image is created using Fritzing. Click to enlarge image

Component Pin	ESP32 Uno Pin
CLK	D9 (GPIO13)
DIO	D10 (GPIO5)
VCC	3.3V
GND	GND

D10 (GPIO5) is a boot strapping pin. The chip reads it during start-up. The TM1637 normally does not disturb it, but if the board fails to boot or upload with the display connected, pull the DIO wire out, upload, and plug it back in.

Good to know: the ESP32 Uno logic is 3.3V, so power the module from 3.3V. The TM1637 works fine at that level and its signal pins are never above 3.3V.

Install the Library and Prepare the Board

By the end of this part, Arduino IDE knows your board and has the display library.

First time with this board? Set it up with ESP32 Uno - Getting Started before you continue.
Build the circuit by following the wiring table above.
Plug in the USB Type-C cable between the ESP32 Uno and your computer.
Select the board in Arduino IDE: pick ESP32 Dev Module and the COM port of the board (CH340).
Open the Library Manager with the Libraries icon in the left bar.
Search for "DIYables_4Digit7Segment_TM1637" and find the entry from DIYables.
Click Install.
Pro tip: after each example below, press the reset button to restart the demo from its first step.

Search for DIYables_4Digit7Segment_TM1637 created by DIYables.io and click the Install button.

Newbiely | Arduino IDE 2.3.8

──

☐

Library Manager

DIYables_4Digit7Segment_TM1637

All

DIYables_4Digit7Segment_TM1637 by DIYables.io

Supports integer display, text, temperature with degree symbol, time with colon separator, brightness control, and individual digit control. Uses 2-wire CLK/DIO interface. Compatible with all Arduino boards. More info

1.0.0

INSTALL

Newbiely.ino

···

1 void setup() {

Output

Serial Monitor

Ln 1, Col 1

ESP32 Dev Module on COM15

Nothing else needs to be installed.

Smallest Working Sketch

By the end of this part, you can read the skeleton that every example on this page shares.

#include <DIYables_4Digit7Segment_TM1637.h> #define CLK_PIN 13 // D9 (GPIO13) goes to CLK #define DIO_PIN 5 // D10 (GPIO5) goes to DIO DIYables_4Digit7Segment_TM1637 display(CLK_PIN, DIO_PIN); void setup() { display.begin(); // start the display driver display.print(1234); // show a number } void loop() { }

Code Part	What It Does
#define CLK_PIN 13	Names the GPIO for the clock line
#define DIO_PIN 5	Names the GPIO for the data line
display(CLK_PIN, DIO_PIN)	Creates the display object on those pins
display.begin()	Prepares the pins once
display.print(1234)	Writes the number to the digits

Create the object with two GPIO numbers, call begin() once, and then write to the display.

Example 1 - Integer Values

By the end of this part, your display counts through several integers and a zero-padded number.

Step 1 — Upload and watch

Make sure the module is wired as in the table above.
Upload the sketch with Upload and open the Serial Monitor at 9600 baud.
Every two seconds the display moves to the next value.

Newbiely | Arduino IDE 2.3.8

──

☐

Newbiely.ino

···

8 Serial.println("Hello World!");

Output

Serial Monitor

Message (Enter to send message to 'ESP32 Dev Module' on 'COM15')

New Line

9600 baud

TM1637 Integer Example Displaying: 0 Displaying: 42 Displaying: 1234 Displaying: -5 Displaying: -123 Displaying: 9999 Displaying: 0042 (zero-padded)

Ln 11, Col 1

ESP32 Dev Module on COM15

The display range is -999 to 9999, so the loop covers both ends.

Methods used

Method	What It Does	Usage
print(int)	Shows an integer from -999 to 9999	display.print(1234)
print(int, true)	Same, with leading zeros	display.print(42, true)
clear()	Turns all segments off	display.clear()

Example 2 - Text and Temperature

By the end of this part, you can print words and temperatures with the degree sign.

/* * This ESP32 Uno code was developed by newbiely.com * * This ESP32 Uno code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp32-uno/esp32-uno-tm1637-4-digit-7-segment-display */ /* * DIYables_4Digit7Segment_TM1637 - TextAndDegree Example * * Shows short words, the degree symbol and temperatures * on a TM1637 4-digit 7-segment display. * * Board: ESP32 Uno (select "ESP32 Dev Module" in Arduino IDE) * Tutorial: https://diyables.io/products/4-digit-7-segment-display-led-tm1637-with-colon */ #include <DIYables_4Digit7Segment_TM1637.h> // Wiring pins - change them if you connect the module elsewhere #define CLK_PIN 13 // D9 (GPIO13) goes to the CLK pin of the module #define DIO_PIN 5 // D10 (GPIO5) goes to the DIO pin of the module DIYables_4Digit7Segment_TM1637 display(CLK_PIN, DIO_PIN); void setup() { Serial.begin(9600); display.begin(); // start the display driver Serial.println("TM1637 Text and Degree Example"); } void loop() { // four short words, each up to 4 characters const char* texts[] = {"HELP", "Hi", "COOL", "done"}; for (int i = 0; i < 4; i++) { display.print(texts[i]); Serial.print("Displaying: "); Serial.println(texts[i]); delay(2000); } // temperature in Celsius with the degree sign display.printTemperature(25, 'C'); // appears as "25°C" Serial.println("Displaying: 25 degrees C"); delay(2000); // temperature in Fahrenheit display.printTemperature(72, 'F'); // appears as "72°F" Serial.println("Displaying: 72 degrees F"); delay(2000); // build the same text by hand with the DEGREE character char buf[5]; buf[0] = '2'; buf[1] = '5'; buf[2] = DIYables_4Digit7Segment_TM1637::DEGREE; buf[3] = 'C'; buf[4] = '\0'; display.print(buf); // gives the same result as printTemperature(25, 'C') Serial.println("Displaying: 25 degrees C (via print)"); delay(2000); }

After the upload, four words appear in turn (HELP, Hi, COOL, done), followed by 25°C and 72°F.

Method	What It Does	Usage
print(const char*)	Shows text of up to 4 characters	display.print("HELP")
printTemperature(int, char)	Shows a value, degree sign and unit	display.printTemperature(25, 'C')
DEGREE	Special character for the degree sign	DIYables_4Digit7Segment_TM1637	DEGREE

Example 3 - Clock with Blinking Colon

By the end of this part, the display shows a clock face with a colon that flashes.

After the upload, the display reads 12:30 and the colon flips every 500 ms.

Method	What It Does	Usage
printTime(int, int)	Shows HH	MM with the colon on	display.printTime(12, 30)
printTime(int, int, bool)	Shows HH	MM and sets the colon	display.printTime(12, 30, false)

Example 4 - Blink the Whole Display

By the end of this part, you can flash the digits while the content stays in memory.

After the upload, 1234 flashes five times, then HELP flashes five times.

Method	What It Does	Usage
off()	Hides the digits, data stays	display.off()
on()	Shows the stored data again	display.on()
setBrightness(int)	Sets the level from 0 to 7	display.setBrightness(4)

Example 5 - Control Single Digits

By the end of this part, you can place a number, a letter or the colon on any position.

/* * This ESP32 Uno code was developed by newbiely.com * * This ESP32 Uno code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp32-uno/esp32-uno-tm1637-4-digit-7-segment-display */ /* * DIYables_4Digit7Segment_TM1637 - IndividualDigits Example * * Sets each digit, each character and the colon one by one * on a TM1637 4-digit 7-segment display. * * Board: ESP32 Uno (select "ESP32 Dev Module" in Arduino IDE) * Tutorial: https://diyables.io/products/4-digit-7-segment-display-led-tm1637-with-colon */ #include <DIYables_4Digit7Segment_TM1637.h> // Wiring pins - change them if you connect the module elsewhere #define CLK_PIN 13 // D9 (GPIO13) goes to the CLK pin of the module #define DIO_PIN 5 // D10 (GPIO5) goes to the DIO pin of the module DIYables_4Digit7Segment_TM1637 display(CLK_PIN, DIO_PIN); void setup() { Serial.begin(9600); display.begin(); // start the display driver Serial.println("TM1637 Individual Digits Example"); } void loop() { // write one number into each of the four positions display.clear(); display.setNumber(0, 1); display.setNumber(1, 2); display.setNumber(2, 3); display.setNumber(3, 4); Serial.println("Displaying: 1234"); delay(2000); // switch the colon on display.setColon(true); Serial.println("Displaying: 12:34"); delay(2000); // switch the colon off again display.setColon(false); Serial.println("Displaying: 1234"); delay(2000); // write one letter into each position display.clear(); display.setChar(0, 'H'); display.setChar(1, 'E'); display.setChar(2, 'L'); display.setChar(3, 'P'); Serial.println("Displaying: HELP"); delay(2000); // letters and numbers together, with the colon on display.clear(); display.setChar(0, 'A'); display.setNumber(1, 3); display.setChar(2, 'b'); display.setNumber(3, 7); display.setColon(true); Serial.println("Displaying: A3:b7"); delay(2000); // show 12:30 and flash the colon five times display.clear(); display.setNumber(0, 1); display.setNumber(1, 2); display.setNumber(2, 3); display.setNumber(3, 0); Serial.println("Blinking colon: 12:30"); for (int i = 0; i < 5; i++) { display.setColon(true); delay(500); display.setColon(false); delay(500); } delay(1000); }

After the upload, the display steps through 1234, 12:34, HELP, A3:b7 and a flashing 12:30.

Method	What It Does	Usage
setNumber(int, int)	Puts a digit 0 to 9 at a position	display.setNumber(0, 1)
setChar(int, char)	Puts a character at a position	display.setChar(0, 'H')
setColon(bool)	Switches the colon on or off	display.setColon(true)
setSegments(int, uint8_t)	Writes raw segment bits	display.setSegments(0, 0x76)

Library Compatibility

The library uses only standard Arduino calls (pinMode, digitalWrite, digitalRead, delayMicroseconds), so it builds for the ESP32 Uno without changes.

ESP32 Uno vs UNO R4 for This Project

By the end of this part, you know what changes when you move the display from the UNO R4 to the ESP32 Uno.

Item	Arduino UNO R4	ESP32 Uno
Logic voltage	5V	3.3V
CLK pin in code	9	13 (D9 is GPIO13)
DIO pin in code	10	5 (D10 is GPIO5)
Module power	5V	3.3V
Arduino IDE board	Arduino UNO R4 WiFi	ESP32 Dev Module
USB driver	none needed	CH340 driver

The wires stay on D9 and D10, so the wiring picture does not change. Only the two numbers in the sketch and the supply wire change.

Go Wireless: Show Messages from Your Phone

By the end of this part, you have an idea to send text to the display from a phone.

The ESP32 Uno has WiFi and Bluetooth built in. Read a number or short word from a web page or a phone app, then pass it to display.print(). Your display becomes a remote message board or a number counter.

Try These Next

Count from 0 to 9999 with a counter that grows once per second.
Lower the brightness at night with setBrightness().
Show a push-button press count on the display.
Build a timer that counts down from 10:00 with the colon on.

Troubleshooting

Problem	Possible Cause	Solution
No COM port appears	CH340 driver missing or charge-only cable	Install the CH340 driver and use a data USB cable
Upload fails with Failed to connect	Board is not in download mode	Hold the BOOT button when the upload starts, release it after Connecting
Board does not boot or upload with the display connected	D10 (GPIO5) is a boot strapping pin and the module pulls it the wrong way	Unplug the DIO wire while uploading, then plug it back in
Display stays dark	VCC or GND wire loose	Check the 3.3V and GND wires and push the jumpers in fully
Display stays dark but wiring looks right	CLK_PIN or DIO_PIN in code differ from the wires	Use 13 for CLK (D9) and 5 for DIO (D10)
Strange symbols on the digits	CLK and DIO swapped	Swap the two signal wires
Display is too dim	Default brightness is low	Call display.setBrightness(7)
Compile error about the TM1637 header	Library not installed	Install DIYables_4Digit7Segment_TM1637 in Library Manager
Colon does not show	Module has no colon wiring or the colon flag is false	Use printTime() with true or setColon(true)

FAQ

What is the TM1637 chip on this display?

It is an LED driver and key-scan chip. It scans the four digits for you and stores what you send. You only need to send new data when the value changes.

Can I power the TM1637 from 5V on the ESP32 Uno?

You can, but 3.3V is the safer choice. At 5V the module could drive its DIO line above 3.3V, which can hurt an ESP32 Uno pin. The module works fine at 3.3V.

Which library should I use for the ESP32 Uno?

Use DIYables_4Digit7Segment_TM1637 from the Library Manager. It builds for the ESP32 Uno without any change and gives you print, printTime and printTemperature.

Can I use different pins for CLK and DIO?

Yes. Any two free output-capable GPIO pins work. Avoid GPIO36 and GPIO39 (A4 and A5 positions), which are input only, because DIO sends data too.

Why does the sketch use 13 and 5 instead of D9 and D10?

The Arduino IDE on the ESP32 Uno needs GPIO numbers. The labels D9 and D10 only help you place wires. In code, D9 maps to 13 and D10 maps to 5.

Do I need the analogSetAttenuation line for this display?

No. The display is digital and uses no analog input, so that line is not in these sketches.

What if my project needs more pins than the Uno headers give?

The ESP32 Uno has extra holes near the power header: GPIO32 and GPIO33 (I/O, PWM, analog on ADC1, so they also work while WiFi is on) and GPIO15 (I/O, PWM, analog on ADC2). Solder pin headers to use them and write the GPIO number in code. For a second TM1637 module, GPIO32 and GPIO33 are the best fit. Two warnings. First, GPIO15 and GPIO0 (the IO0 pin at the unused Uno NC position) are boot strapping pins, and a wrong connection can stop the board from booting or uploading code, so use GPIO32 and GPIO33 first. Second, never use the six holes under the digital header (SD0 to SD3, CMD, CLK = GPIO6 to GPIO11). They are wired to the flash chip and using them crashes the board.

Is it possible to run two TM1637 modules on one board?

Yes. Give each display its own CLK and DIO pair and create two objects. They can also share one CLK line with separate DIO pins.

Do I need a resistor between the board and the module?

No. The module has its own parts on board, so direct jumper wires are fine.

How is this different from the UNO R4 sketch?

Only the pin numbers change, from 9 and 10 to 13 and 5. The library calls are the same.

Can I make a real clock with the ESP32 Uno?

Yes. Get the time from an RTC module or from the internet over WiFi, then pass the hours and minutes to printTime(). The ESP32 Uno can get the time from the network with no extra hardware.

Can I show the display value on a web page too?

Yes. The ESP32 Uno has WiFi, so you can send the same number to a web page, or accept a number from a phone and show it on the display.

Learn More

ESP32 UNO - 74HC595 4-Digit 7-Segment Display

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