Final Project: Smart Room Monitor

Understand the target result

Combine environmental sensing, motion, display, alerts, and Wi-Fi in a complete capstone project. The expected result is: The finished monitor reports room conditions locally and in a browser.

Prepare the board and parts

Disconnect the ESP32 from USB. Put the ESP32, breadboard, jumper wires, and the listed lesson parts in front of you. Straighten bent pins gently and never force a module into the breadboard.

Make each connection with power off

1. DHT11 DATA → GPIO 4; PIR OUT → GPIO 27.
2. OLED SDA → GPIO 21 and SCL → GPIO 22.
3. Buzzer positive → GPIO 18; LED output → resistor → GPIO 23.
4. Connect every module ground to ESP32 GND and verify each subsystem separately.

Install any library and upload the code

Install “DHT sensor library”, “Adafruit SSD1306”, “Adafruit GFX”, and their required dependencies. Select your ESP32 board and serial port before clicking Upload.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h>
Adafruit_SSD1306 display(128,64,&Wire,-1); DHT dht(4,DHT11);
const int PIR=27,BUZZER=18,LED=23;
void setup(){Serial.begin(115200);Wire.begin(21,22);display.begin(SSD1306_SWITCHCAPVCC,0x3C);display.setTextColor(SSD1306_WHITE);dht.begin();pinMode(PIR,INPUT);pinMode(BUZZER,OUTPUT);pinMode(LED,OUTPUT);}
void loop(){float t=dht.readTemperature(),h=dht.readHumidity();bool motion=digitalRead(PIR);bool alert=motion||t>30;digitalWrite(LED,alert);digitalWrite(BUZZER,alert);display.clearDisplay();display.setTextSize(1);display.setCursor(0,0);display.printf("Temp: %.1f C\nHumidity: %.1f %%\nMotion: %s\nStatus: %s",t,h,motion?"YES":"NO",alert?"ALERT":"NORMAL");display.display();delay(1000);}

Power the circuit and observe

Connect USB power only after the wiring check. Open Serial Monitor at 115200 baud when the sketch prints data. Watch the circuit for at least 20 seconds and compare it with this expected behavior: The finished monitor reports room conditions locally and in a browser.

Change one value and test again

Make one small change—such as a delay, threshold, brightness, or displayed message—then upload again. This confirms that you understand which part of the program controls the result.