🌡️ DHT22 Temperature and Humidity Sensor for Raspberry Pi Pico W

🔌 Wiring Diagram

DHT22 Sensor              Raspberry Pi Pico W
══════════════            ════════════════════
VCC (Pin 1)     ─────►    3.3V (Pin 36)
GND (Pin 4)     ─────►    GND (Pin 38)
DATA (Pin 2)    ─────►    GP0 (Pin 1)

⚠️ IMPORTANT: Add 10kΩ pull-up resistor between DATA and 3.3V!
    
    3.3V ──┬── 10kΩ ──┬── DHT22 DATA
           │          │
           └──────────┴── Pico GP0
    
    DHT22 pins (front view, pins facing you):
    ┌─────────────┐
    │ (1) VCC     │
    │ (2) DATA    │
    │ (3) NC      │
    │ (4) GND     │
    └─────────────┘
    

📦 Install DHT Library in Thonny

1. Open Thonny IDE
2. Click Tools → Manage Packages
3. Search for "micropython-dht"
4. Click Install

📖 Complete MicroPython Code

import dht
from machine import Pin
import time

# Initialize DHT22 on GP0
sensor = dht.DHT22(Pin(0))

print("🌡️ DHT22 Weather Monitor Started")
print("=================================")

while True:
    try:
        # Measure sensor (takes 0.5-1 second)
        sensor.measure()
        
        # Read values
        temp = sensor.temperature()
        hum = sensor.humidity()
        
        # Display results
        print(f"\n🌡️ Temperature: {temp}°C | {temp * 9/5 + 32:.1f}°F")
        print(f"💧 Humidity: {hum}%")
        
        # Alerts
        if temp > 35:
            print("⚠️ HEAT WARNING! Increase ventilation/irrigation")
        elif temp < 10:
            print("⚠️ COLD! Protect sensitive crops from frost")
        
        if hum > 85:
            print("⚠️ HIGH HUMIDITY! Risk of fungal disease")
        elif hum < 30:
            print("⚠️ LOW HUMIDITY! Plants under stress")
        
    except Exception as e:
        print("❌ Sensor error:", e)
        print("   Check wiring and pull-up resistor")
    
    time.sleep(10)  # Read every 10 seconds