92 lines
2.9 KiB
Markdown
92 lines
2.9 KiB
Markdown
---
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active: false
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tags: project
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created: 2026-05-28 15:23
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---
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## Summary
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Building an I2C temperature controller involves reading temperature from an I2C sensor (like an MCP9808 or DHT12) and using an Arduino to trigger a relay (for heaters/coolers) or adjust a fan. Use the standard `<Wire.h>` library for communication and control relays based on your temperature thresholds.
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Here is a straightforward guide to get your project running.
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🛠️ Hardware Requirements
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- **Microcontroller:** Arduino Uno or Nano
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- **I2C Temperature Sensor:** MCP9808 (High precision) or DHT12
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- **I2C Display (Optional):** 16x2 LCD with I2C backpack (PCF8574)
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- **Control Element:** 5V Relay module (to switch a fan or heater)
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- **Misc:** Breadboard, jumper wires, and 4.7kΩ pull-up resistors (if not built into your sensor modules)
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🔌 Wiring the Components
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Connect your I2C devices to the Arduino's I2C bus. You will share these lines between the sensor and the display.
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- **VCC** Arduino
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- **GND** Arduino
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- **SDA** Arduino Analog Pin (or the dedicated pin on newer boards)
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- **SCL** Arduino Analog Pin (or the dedicated pin on newer boards)
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- **Relay Signal Pin** Arduino Digital Pin
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Before running this code, ensure you have installed the **Adafruit MCP9808 Library** and the **LiquidCrystal_I2C Library** via the Arduino IDE Library Manager (`Sketch > Include Library > Manage Libraries`).
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```
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#include <Wire.h>
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#include <Adafruit_MCP9808.h>
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#include <LiquidCrystal_I2C.h>
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// Create sensor and display objects
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Adafruit_MCP9808 tempsensor = Adafruit_MCP9808();
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LiquidCrystal_I2C lcd(0x27, 16, 2); // Set the LCD address to 0x27 for a 16 chars and 2 line display
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const int RELAY_PIN = 7;
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const float TARGET_TEMP = 25.0; // Target temperature in Celsius
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const float HYSTERESIS = 0.5; // Prevents relay rapid switching (chattering)
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void setup() {
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Serial.begin(9600);
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pinMode(RELAY_PIN, OUTPUT);
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digitalWrite(RELAY_PIN, HIGH); // Default to OFF (Relays are often active LOW)
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// Initialize I2C LCD
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lcd.init();
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lcd.backlight();
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lcd.setCursor(0, 0);
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lcd.print("I2C Temp Ctrl");
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// Initialize sensor
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if (!tempsensor.begin(0x18)) { // Default I2C address for MCP9808
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Serial.println("Couldn't find MCP9808!");
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while (1);
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}
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tempsensor.setResolution(3); // Set resolution to 0.0625°C
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}
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void loop() {
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tempsensor.wake(); // Wake up sensor
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float tempC = tempsensor.readTempC();
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tempsensor.shutdown(); // Shutdown to save power/reduce self-heating
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// Update Display
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lcd.setCursor(0, 1);
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lcd.print("Temp: ");
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lcd.print(tempC);
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lcd.print("C");
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// Temperature Control Logic
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if (tempC > (TARGET_TEMP + HYSTERESIS)) {
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digitalWrite(RELAY_PIN, LOW); // Turn ON cooling/heating
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}
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else if (tempC < (TARGET_TEMP - HYSTERESIS)) {
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digitalWrite(RELAY_PIN, HIGH); // Turn OFF cooling/heating
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}
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delay(1000); // Read temperature every second
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}
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```
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## Tasks
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## References
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