Let’s build.
You can complete the first version entirely offline. Do not collect personal information in a shared classroom.
Sensor operates on 3.3V logic. Connecting data pin directly to 5V without pull-up may damage ESP32 ADC/GPIO pins.
Hardware Bill of Materials (BOM)
Circuit Wiring & Pin-to-Pin Connection Matrix
ESP32 3.3V PinDHT22 Pin 1 (VCC)RedClean 3.3V regulated power railESP32 GPIO 4 (D4)DHT22 Pin 2 (Data)Yellow1-Wire bidirectional digital telemetry data busESP32 GND PinDHT22 Pin 4 (GND)BlackCommon reference ground connectionStep-by-Step Assembly & Verification Guide
- 01
Choose one measurement such as temperature. Use a sensor supported by your controller and follow its wiring guide.
- 02
Read the sensor locally and compare it with a reference where available. Record units and expected accuracy.
- 03
Collect a reading at a consistent interval. Store the timestamp, device ID and value in a CSV file.
- 04
Plot the readings and mark any missing values. Describe the conditions under which you collected the data.
- 05
As an extension, send readings to your own authenticated endpoint. Keep credentials private and handle network failures.
Reference Firmware Sketch (CPP)
// iSpark IoT Lab: Precision Environmental Sensor Journal
// Sensor: DHT22 | Controller: ESP32 NodeMCU
#include "DHT.h"
#define DHTPIN 4
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);
void setup() {
Serial.begin(115200);
Serial.println("[iSpark IoT] Environmental Journal Station starting...");
dht.begin();
}
void loop() {
delay(2000); // 2-second sampling interval
float humidity = dht.readHumidity();
float temperature = dht.readTemperature();
if (isnan(humidity) || isnan(temperature)) {
Serial.println("ERR: Failed to read from DHT22 sensor! Check wiring.");
return;
}
// Format timestamped CSV output for logging
Serial.printf("LOG,%lu,%.2f,%.2f,CELSIUS,PERCENT\n", millis(), temperature, humidity);
}An introductory learning resource, not an accredited qualification. Check the documentation for your exact hardware and work with appropriate supervision.