Fix LM35 Wrong Values in Arduino & Proteus: Ultimate Wiring Guide
Published on January 1, 2025 | By ArduinoUnoProjex
Struggling with incorrect LM35 temperature sensor values in your Arduino or Proteus projects? This comprehensive guide reveals how to fix LM35 wrong values by correcting wiring issues, not code. Learn to troubleshoot, wire the LM35 correctly, and achieve accurate temperature readings with our step-by-step instructions and sample code. Start with our recommended products and master Arduino LM35 projects!
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Why Does the LM35 Give Wrong Values?
Why is my LM35 sensor giving incorrect readings in Arduino or Proteus? Incorrect values often stem from wiring errors, not faulty code. Issues like reversed pins, improper power connections, or missing ground can cause erratic or zero readings. This Arduino LM35 troubleshooting guide focuses on fixing wiring to ensure accurate temperature data.
Common Symptoms: Zero output, negative values, or fluctuating readings despite correct code.
Components Needed
To troubleshoot and build a reliable LM35 Arduino temperature project, gather these components:
- ✅Arduino Uno or ELEGOO Uno R3 (Arduino IDE-compatible)
- ✅LM35 Temperature Sensor
- ✅Breadboard & Jumper Wires
- ✅USB Cable for Arduino
Optional: USB-to-Serial module (e.g., CH340) for debugging, or a multimeter to verify voltages.
Step-by-Step Troubleshooting for LM35 Wrong Values
How do I fix incorrect LM35 readings in Arduino or Proteus? Follow these steps to diagnose and correct wiring issues.
Step 1: Verify Initial Readings
Start by checking the LM35 output. Incorrect readings, like those shown below, suggest a wiring issue.
Step 2: Check LM35 Wiring
The LM35 has three pins: VCC, OUT, and GND. Incorrect connections are the primary cause of wrong values.
Wiring Instructions
Power Connection (VCC): Connect the LM35 VCC pin to Arduino’s 5V pin.
Output Connection (OUT): Connect the LM35 OUT pin to Arduino’s analog pin A0.
Ground Connection (GND): Connect the LM35 GND pin to Arduino’s GND pin.
Verify Connections: Ensure no loose wires and check pin orientation (LM35’s flat side faces left: VCC, OUT, GND from left to right).
💡Tip: In Proteus, ensure the LM35 model is correctly configured with a 5V supply and analog input to the Arduino.
Step 3: Test Corrected Wiring
After rewiring, you should see accurate readings, as shown below.
Sample Arduino Code for LM35
What code reads accurate LM35 temperature values? Use this code to test your LM35 after correcting wiring.
const int lm35Pin = A0; // LM35 output pin
void setup() {
Serial.begin(9600); // Start serial monitor
}
void loop() {
int rawValue = analogRead(lm35Pin); // Read analog value
float voltage = (rawValue / 1023.0) * 5000; // Convert to millivolts
float tempC = voltage / 10; // Convert to Celsius (LM35: 10mV/°C)
Serial.print("Temperature: ");
Serial.print(tempC);
Serial.println(" °C");
delay(1000); // Update every second
}
Code Breakdown
- Pin Definition:
lm35Pinset to A0 for LM35 output. - Setup: Initializes Serial monitor for debugging.
- Loop: Reads analog value, converts to voltage (0-5V), then to Celsius (10mV/°C).
- Output: Prints temperature to Serial monitor every second.
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Testing the LM35 Setup
How do I test my LM35 after fixing wiring? Follow these steps to verify accurate readings.
Upload Code: Connect Arduino to your computer and upload the sample code via Arduino IDE.
Open Serial Monitor: Set baud rate to 9600 and observe temperature readings.
Test Sensor: Gently heat the LM35 (e.g., with your finger) or cool it to see temperature changes.
Expected Result: Serial monitor shows stable temperatures (e.g., ~25°C at room temperature).
💡Tip: In Proteus, simulate temperature changes by adjusting the LM35 model’s temperature parameter.
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LM35 vs. TMP36: A Comparison
How does the LM35 compare to the TMP36? Both are popular temperature sensors, but they differ in key ways.
| Feature | LM35 | TMP36 |
|---|---|---|
| Output Scale | 10mV/°C | 10mV/°C, offset at 500mV |
| Temperature Range | 0°C to 100°C | -40°C to 125°C |
| Power Supply | 4V to 30V | 2.7V to 5.5V |
| Negative Temps | Requires additional circuit | Supports directly |
Recommendation: Use LM35 for simple projects with positive temperatures; choose TMP36 for wider ranges or negative readings.
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Troubleshooting Tips for LM35
- ⚠️Zero or Negative Readings: Check VCC (5V) and GND connections; ensure LM35 orientation is correct.
- ⚠️Fluctuating Values: Add a 0.1µF capacitor between VCC and GND to stabilize power.
- ⚠️Proteus Errors: Verify LM35 model settings (5V supply, analog output) and simulation clock speed.
- ⚠️No Output: Use a multimeter to check LM35 output voltage (~250mV at 25°C).
Advanced LM35 Project Ideas
- 🚀Add an LCD to display temperature in real-time.
- 🚀Integrate an ESP8266 to log temperature data to a cloud server.
- 🚀Use a relay to control a fan based on temperature thresholds.
- 🚀Simulate a thermostat in Proteus with multiple LM35 sensors.
Frequently Asked Questions
Why is my LM35 giving wrong values in Arduino or Proteus?
Incorrect wiring, such as reversed VCC/GND pins or loose connections, is the most common cause. Connect VCC to 5V, OUT to A0, and GND to GND.
How do I wire the LM35 temperature sensor correctly?
Connect the LM35 VCC pin to Arduino 5V, OUT pin to A0, and GND pin to Arduino GND. Ensure the flat side faces left (VCC, OUT, GND from left to right).
Can I use ELEGOO boards for LM35 projects?
Yes, ELEGOO boards like Uno R3 are fully compatible with Arduino IDE and work perfectly with the LM35 sensor.
Conclusion
This LM35 Arduino troubleshooting guide equips you to fix incorrect temperature readings by correcting wiring errors in both physical setups and Proteus simulations. With proper connections (VCC to 5V, OUT to A0, GND to GND), you’ll achieve accurate results. Explore our recommended products, try the sample code, and check out our Arduino tutorials for more projects. Share your LM35 success stories in the comments and join the maker community! 🌡️
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