How do you securely mount an Arduino Uno and 1602 LCD inside a Lego brick chassis?

Standard Lego studs have an 8mm pitch spacing. An Arduino Uno PCB mounting hole spacing does not align perfectly with Lego stud dimensions, so makers use 3D-printed Lego-compatible mounting baseplates or build snug brick friction-fit framing walls. For the 1602 LCD, build a bezel frame that holds the PCB ears behind a 2-stud-wide border, leaving the active glass display recessed and protected.

How are multiple I2C and digital components wired inside the Lego clock?

The DS3231 RTC and I2C LCD backpack share the Uno I2C bus on Analog Pin A4 (SDA) and Analog Pin A5 (SCL) with shared 5V and GND power rails. The DHT11 temperature and humidity sensor connects to a separate digital pin (Digital Pin 2) with a 10kΩ pull-up resistor. All power lines terminate at a compact mini-breadboard or soldered distribution bus inside the Lego housing.

How do you display Time, Date, Temperature, and Humidity across only two LCD rows?

Use a non-blocking millis() timer state machine in your Arduino loop to alternate between display pages every 3 to 5 seconds. Page 1 displays "TIME: HH:MM:SS" on Row 0 and "DATE: MM/DD/YYYY" on Row 1. Page 2 displays "TEMP: 72F (22C)" on Row 0 and "HUMIDITY: 45%" on Row 1. This rotates all essential metrics without screen clutter or erratic text scrolling.

What is the recommended power supply for running this Lego clock 24/7 on a desk?

Power the Arduino Uno via its standard USB Type-B port using a regulated 5V 1A or 2A USB wall adapter (such as a standard phone charger). Avoid using a 9V PP3 alkaline battery for continuous operation, as an Arduino Uno and backlit LCD draw approximately 60mA–80mA, exhausting a standard 9V battery in less than 8 hours. The DS3231 coin cell ensures timekeeping continuity during power outages or unplugging.

How does this Lego clock build integrate with VTM Studio?

This project pairs with VTM Studio Layout Mode (for measuring Lego brick cavity dimensions and component clearances) and Reference Mode (for unified I2C wiring diagrams). Code Mode compiles and uploads the multi-page clock firmware, while Science Mode streams live temperature and humidity telemetry to calibrate sensor offsets.

Arduino | Lego Clock | My First Build

Arduino | Lego Clock | My First Build - VTM Systems Store

Direct Technical Summary For the last 2 1/2 months I've been learning Arduino. After practicing some real time clock, I2C LCD and temperature and humidity sensor projects I was eager to make my first build. I guess all makers have all been there at some point! That's where I am. As a result of all my beginner Arduino projects and tutorials on YouTube I was ready to give a basic Lego clock a go. I know its been done and overdone, but I like Arduino and I like Legos, so why not?

Lego Clock | First Build

Arduino Project

For the last 2 1/2 months I've been learning Arduino. After practicing some real time clock, I2C LCD and temperature and humidity sensor projects I was eager to make my first build. I guess all makers have all been there at some point! That's where I am. As a result of all my beginner Arduino projects and tutorials on YouTube I was ready to give a basic Lego clock a go. I know its been done and overdone, but I like Arduino and I like Legos, so why not?

As I began preparing to build this Lego clock I realized how practical it was to use Legos for an Arduino project. It's a great way to create an initial build after a prototype.

Legos, DS3231, I2C LCD and Arduino Nano

Make sure to make all connections before powering up your Arduino.

Arduino Tutorial Video

LEVELS

Difficulty 20%
Fun 90%

Skills Practice

Electronics

Making connections

Visuino

Visual Programming

Arduino IDE

Basic Arduino IDE functions

RTC Practice

Using a DS3231

I2C LCD Practice

Using an I2C LCD

LEGO Building

Using Legos to build/prototype

Video Production

Setting up a video shoot

Components, Boards and Parts

arduino nano

Arduino Uno, Mega or Nano

Qty=1

Buy on Amazon

dht11

DS3231 AT24C32 I2C RTC

Qty=1

Buy on Amazon

dht11

I2C 16 x 2 LCD Display

Qty=1

Buy on Amazon

arduino uno

Female to Male Jumper Wires

Qty=8

Buy on Amazon

breadboard

400 Points Solderless Breadboard

Qty=1

Buy on Amazon

The Lego Arduino Clock

This was a fun shoot.

Software and Apps

arduino uno

Arduino IDE or Web Editor

Visit Arduino

The Code

STANDARD ARDUINO C++ CLOCK SKETCH (OFFLINE / FAST COPY)

Maker Tip: Upload this clock sketch directly using the Arduino IDE or VTM Studio Code Mode.

/*
 * VTM Arduino Tutorial: Lego Clock DS3231 RTC + 1602 I2C LCD
 * Tutorial: Arduino | Lego Clock | My First Build
 * 
 * Hardware Connections:
 *   DS3231 & 1602 LCD VCC -> Arduino 5V
 *   DS3231 & 1602 LCD GND -> Arduino GND
 *   DS3231 & 1602 LCD SDA -> Arduino Pin A4 (Uno) or SDA
 *   DS3231 & 1602 LCD SCL -> Arduino Pin A5 (Uno) or SCL
 * 
 * Libraries: RTClib by Adafruit, LiquidCrystal_I2C
 */

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include "RTClib.h"

RTC_DS3231 rtc;
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Wire.begin();
  lcd.init();
  lcd.backlight();

  if (!rtc.begin()) {
    lcd.setCursor(0, 0);
    lcd.print("RTC Error!");
    while (1);
  }

  lcd.clear();
}

void loop() {
  DateTime now = rtc.now();

  char dateBuffer[17];
  snprintf(dateBuffer, sizeof(dateBuffer), "Date: %04d-%02d-%02d", 
           now.year(), now.month(), now.day());
  lcd.setCursor(0, 0);
  lcd.print(dateBuffer);

  char timeBuffer[17];
  snprintf(timeBuffer, sizeof(timeBuffer), "Time: %02d:%02d:%02d", 
           now.hour(), now.minute(), now.second());
  lcd.setCursor(0, 1);
  lcd.print(timeBuffer);

  delay(1000);
}