Arduino Nano ESP32 - 74HC595 4-Digit 7-Segment Display
Welcome to this hands-on workshop where we connect a 74HC595 4-digit 7-segment display module to an Arduino Nano ESP32. The Nano ESP32 is built around the ESP32-S3 chip, giving you Wi-Fi, Bluetooth Low Energy, and dual-core processing power - all packed into the familiar Nano form factor with a USB-C connector.
In this workshop you will:
- Wire the 74HC595 display module to the Arduino Nano ESP32.
- Show integers, floats, and text on the display.
- Display temperature readings with a degree symbol.
- Present time in HH.MM format with a blinking separator.
Hardware Preparation
Or you can buy the following kits:
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Additionally, some of these links are for products from our own brand, DIYables .
Overview of the 74HC595 4-Digit 7-Segment Display
This compact module pairs four 7-segment digits with a 74HC595 shift register. Data is shifted in serially through 3 pins and then latched to the LED segments. The library handles the digit multiplexing automatically - you set a value with print() and the display keeps showing it.
| Function | Pin | Description |
|---|---|---|
| SCLK (SH_CP) | Serial Clock | Clocks data bits into the register |
| RCLK (ST_CP) | Register Clock | Latches shifted data to outputs |
| DIO (DS) | Data Input | Serial data line |
| VCC | Power | 3.3V or 5V |
| GND | Ground | Common ground |
Note: The Arduino Nano ESP32 operates at 3.3V. The 74HC595 module works at 3.3V without issues.
Wiring Diagram
Connect the display to the Nano ESP32:
- SCLK to D7
- RCLK to D6
- DIO to D5
- VCC to 3.3V
- GND to GND
This image is created using Fritzing. Click to enlarge image
Library Setup
- Plug the Arduino Nano ESP32 into your computer through its USB-C port.
- Open Arduino IDE. Pick Arduino Nano ESP32 from the board list and select the right port.
- Click the Libraries icon on the left sidebar.
- Type "DIYables_4Digit7Segment_74HC595" in the search field. Find the DIYables entry.
- Hit Install. Select version 2.0.0 or later.
Self-contained library - nothing else to install.
Starter Sketch
The minimum code needed to get going:
#include <DIYables_4Digit7Segment_74HC595.h>
#define SCLK_PIN D7
#define RCLK_PIN D6
#define DIO_PIN D5
DIYables_4Digit7Segment_74HC595 display(SCLK_PIN, RCLK_PIN, DIO_PIN);
void setup() {
display.begin();
display.print(1234);
}
void loop() {
display.loop();
}
begin() sets up the pins. loop() handles multiplexing - call it as often as possible. Use display.delay() instead of delay() to keep the display alive during waits.
Workshop - Display Integers
Shows integers from -999 to 9999, including zero-padded output.
/*
* This Arduino Nano ESP32 code was developed by newbiely.com
*
* This Arduino Nano ESP32 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-74hc595-4-digit-7-segment-display
*/
#include <DIYables_4Digit7Segment_74HC595.h>
// Pin configuration - change these to match your wiring
#define SCLK_PIN D7 // The Arduino Nano ESP32 pin connected to the Serial clock pin of 7-segment display
#define RCLK_PIN D6 // The Arduino Nano ESP32 pin connected to the Register clock / latch pin of 7-segment display
#define DIO_PIN D5 // The Arduino Nano ESP32 pin connected to the Data (DS) pin of 7-segment display
DIYables_4Digit7Segment_74HC595 display(SCLK_PIN, RCLK_PIN, DIO_PIN);
int numbers[] = {0, 42, 1234, -5, -123, 9999};
int numCount = 6;
int currentIndex = 0;
bool showZeroPad = false;
unsigned long lastChange = 0;
void setup() {
Serial.begin(9600);
display.begin();
Serial.println("4-Digit 7-Segment 74HC595 - Integer Example");
}
void loop() {
display.loop(); // Must be called frequently to refresh the display
if (millis() - lastChange >= 2000) {
lastChange = millis();
if (!showZeroPad) {
display.print(numbers[currentIndex]);
Serial.print("Displaying: ");
Serial.println(numbers[currentIndex]);
currentIndex++;
if (currentIndex >= numCount) {
currentIndex = 0;
showZeroPad = true;
}
} else {
display.print(42, true); // Shows "0042"
Serial.println("Displaying: 0042 (zero-padded)");
showZeroPad = false;
}
}
}
Hands-On
- Wire the display to the Nano ESP32 as described above.
- Connect the Nano ESP32 to your computer via USB-C.
- In Arduino IDE, choose the board and port, paste the code, and click Upload.
- Open the Serial Monitor to observe the results.
The display cycles through 0, 42, 1234, -5, -123, 9999, then 0042 (zero-padded).
Method Reference
| Method | Action | Syntax |
|---|---|---|
| print(int) | Display an integer | display.print(1234) |
| print(int, true) | Integer with zero-padding | display.print(42, true) |
| loop() | Refresh the display | display.loop() |
Workshop - Display Floats
Floating-point numbers with auto and fixed decimals.
/*
* This Arduino Nano ESP32 code was developed by newbiely.com
*
* This Arduino Nano ESP32 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-74hc595-4-digit-7-segment-display
*/
#include <DIYables_4Digit7Segment_74HC595.h>
// Pin configuration - change these to match your wiring
#define SCLK_PIN D7 // The Arduino Nano ESP32 pin connected to the Serial clock pin of 7-segment display
#define RCLK_PIN D6 // The Arduino Nano ESP32 pin connected to the Register clock / latch pin of 7-segment display
#define DIO_PIN D5 // The Arduino Nano ESP32 pin connected to the Data (DS) pin of 7-segment display
DIYables_4Digit7Segment_74HC595 display(SCLK_PIN, RCLK_PIN, DIO_PIN);
void setup() {
Serial.begin(9600);
display.begin();
Serial.println("4-Digit 7-Segment 74HC595 - Float Example");
}
void loop() {
// Auto decimal placement
display.print(1.5); // Shows " 1.5"
Serial.println("Auto decimal: 1.5");
display.delay(2000);
display.print(12.34); // Shows "12.34"
Serial.println("Auto decimal: 12.34");
display.delay(2000);
display.print(3.141); // Shows "3.141"
Serial.println("Auto decimal: 3.141");
display.delay(2000);
display.print(-1.2); // Shows "-1.20"
Serial.println("Auto decimal: -1.20");
display.delay(2000);
display.print(0.5); // Shows " 0.5"
Serial.println("Auto decimal: 0.5");
display.delay(2000);
// Fixed decimal places
display.print(23.5, 1); // 1 decimal place: shows "23.5"
Serial.println("1 decimal place: 23.5");
display.delay(2000);
display.print(1.5, 2); // 2 decimal places: shows "1.50"
Serial.println("2 decimal places: 1.50");
display.delay(2000);
// Zero-padded
display.print(1.5, 2, true); // Shows "01.50"
Serial.println("2 decimal places, zero-padded: 01.50");
display.delay(2000);
}
Hands-On
- Upload the code and open the Serial Monitor.
Shows auto-decimal floats, then fixed 1 and 2 decimal places, and zero-padded.
Workshop - Text and Temperature
Text strings, degree symbol, and temperature display.
/*
* This Arduino Nano ESP32 code was developed by newbiely.com
*
* This Arduino Nano ESP32 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-74hc595-4-digit-7-segment-display
*/
#include <DIYables_4Digit7Segment_74HC595.h>
// Pin configuration - change these to match your wiring
#define SCLK_PIN D7 // The Arduino Nano ESP32 pin connected to the Serial clock pin of 7-segment display
#define RCLK_PIN D6 // The Arduino Nano ESP32 pin connected to the Register clock / latch pin of 7-segment display
#define DIO_PIN D5 // The Arduino Nano ESP32 pin connected to the Data (DS) pin of 7-segment display
DIYables_4Digit7Segment_74HC595 display(SCLK_PIN, RCLK_PIN, DIO_PIN);
const char* texts[] = {"HELP", "Hi", "COOL", "done"};
int textCount = 4;
int currentIndex = 0;
int phase = 0;
unsigned long lastChange = 0;
void setup() {
Serial.begin(9600);
display.begin();
Serial.println("4-Digit 7-Segment 74HC595 - Text and Degree Example");
}
void loop() {
display.loop(); // Must be called frequently to refresh the display
if (millis() - lastChange >= 2000) {
lastChange = millis();
if (phase == 0) {
// Display text strings
display.print(texts[currentIndex]);
Serial.print("Text: ");
Serial.println(texts[currentIndex]);
currentIndex++;
if (currentIndex >= textCount) {
currentIndex = 0;
phase = 1;
}
} else if (phase == 1) {
// Display temperature 25 degrees C
display.printTemperature(25, 'C');
Serial.println("Temperature: 25 C");
phase = 2;
} else if (phase == 2) {
// Display temperature 72 degrees F
display.printTemperature(72, 'F');
Serial.println("Temperature: 72 F");
phase = 3;
} else if (phase == 3) {
// Display degree symbol using string with DEGREE_CHAR constant
char degStr[5];
degStr[0] = '2';
degStr[1] = '5';
degStr[2] = DEGREE_CHAR;
degStr[3] = 'C';
degStr[4] = '\0';
display.print(degStr);
Serial.println("String with degree: 25 deg C");
phase = 4;
} else {
// Display string with dots
display.print("1.2.3.4");
Serial.println("Dots: 1.2.3.4");
phase = 0;
}
}
}
Hands-On
- Upload the code and open the Serial Monitor.
Shows "HELP", "Hi", "COOL", "done", temperatures, and inline dots.
Workshop - Time
Clock-style HH.MM with blinking dot.
/*
* This Arduino Nano ESP32 code was developed by newbiely.com
*
* This Arduino Nano ESP32 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-74hc595-4-digit-7-segment-display
*/
#include <DIYables_4Digit7Segment_74HC595.h>
// Pin configuration - change these to match your wiring
#define SCLK_PIN D7 // The Arduino Nano ESP32 pin connected to the Serial clock pin of 7-segment display
#define RCLK_PIN D6 // The Arduino Nano ESP32 pin connected to the Register clock / latch pin of 7-segment display
#define DIO_PIN D5 // The Arduino Nano ESP32 pin connected to the Data (DS) pin of 7-segment display
DIYables_4Digit7Segment_74HC595 display(SCLK_PIN, RCLK_PIN, DIO_PIN);
int hours = 12;
int minutes = 30;
bool colonOn = true;
unsigned long lastToggle = 0;
void setup() {
Serial.begin(9600);
display.begin();
Serial.println("4-Digit 7-Segment 74HC595 - Time Example");
Serial.println("Displaying 12:30 with blinking dot separator");
}
void loop() {
display.loop(); // Must be called frequently to refresh the display
if (millis() - lastToggle >= 500) {
lastToggle = millis();
display.printTime(hours, minutes, colonOn);
colonOn = !colonOn; // Toggle dot separator every 500ms for blinking effect
}
}
Hands-On
- Upload the code and open the Serial Monitor.
Displays 12.30 with the dot blinking every 500ms.
Workshop - Blink
Blinks display content on and off.
/*
* This Arduino Nano ESP32 code was developed by newbiely.com
*
* This Arduino Nano ESP32 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-74hc595-4-digit-7-segment-display
*/
#include <DIYables_4Digit7Segment_74HC595.h>
// Pin configuration - change these to match your wiring
#define SCLK_PIN D7 // The Arduino Nano ESP32 pin connected to the Serial clock pin of 7-segment display
#define RCLK_PIN D6 // The Arduino Nano ESP32 pin connected to the Register clock / latch pin of 7-segment display
#define DIO_PIN D5 // The Arduino Nano ESP32 pin connected to the Data (DS) pin of 7-segment display
DIYables_4Digit7Segment_74HC595 display(SCLK_PIN, RCLK_PIN, DIO_PIN);
// States: 0 = blink int, 1 = blink float, 2 = blink text
int phase = 0;
int blinkCount = 0;
bool isOn = true;
unsigned long lastAction = 0;
unsigned long pauseUntil = 0;
void setup() {
Serial.begin(9600);
display.begin();
Serial.println("4-Digit 7-Segment 74HC595 - Blink Example");
display.print(1234);
Serial.println("Blinking: 1234");
}
void loop() {
display.loop(); // Must be called frequently to refresh the display
unsigned long now = millis();
// Pause between phases
if (now < pauseUntil) return;
if (now - lastAction >= 300) {
lastAction = now;
if (isOn) {
display.off();
isOn = false;
} else {
display.on();
isOn = true;
blinkCount++;
if (blinkCount >= 5) {
blinkCount = 0;
pauseUntil = now + 1000;
phase++;
if (phase > 2) phase = 0;
switch (phase) {
case 0:
display.print(1234);
Serial.println("Blinking: 1234");
break;
case 1:
display.print(12.34);
Serial.println("Blinking: 12.34");
break;
case 2:
display.print("HELP");
Serial.println("Blinking: HELP");
break;
}
}
}
}
}
Hands-On
- Upload the code and open the Serial Monitor.
Blinks 1234, then 12.34, then "HELP" - five times each.
Troubleshoot
| Issue | Possible Cause | Resolution |
|---|---|---|
| Display blank | Wiring problem | Check VCC, GND, and data pin connections |
| Wrong characters | Anode/cathode mismatch | Pass false to constructor for common cathode |
| Flickering | delay() blocking loop() | Use display.delay() instead |
| Upload fails | Board in wrong mode | Hold the BOOT button while pressing RESET, then retry upload |
Platform Support
The library is built entirely on Arduino standard APIs and supports all Arduino-compatible platforms (architectures=*).