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measuring-temperatures-with-lm35-and-ds18b20-fee8f8-en.md

This design is a simple way to get temperatures from two sensors, thus obtaining an average value. All values are sent by bluetooth, but the average temperature makes a set of LEDs light up according to some parameters.

EXPANDED TECHNICAL DETAILS

Sensor Comparison & Logic

This project focuses on the differences between analog and digital temperature measurement.

  • LM35 (Analog): Outputs 10mV/°C. The Arduino reads this via a 10-bit ADC.
  • DS18B20 (Digital): Communicates over the 1-Wire bus. It provides higher precision (up to 0.0625°C increments) and is more resistant to electrical noise over long cable runs.

Multi-Node Monitoring

The firmware implements a comparison logic:

  1. Parallel Read: Both sensors are sampled simultaneously.
  2. Error Calculation: The system identifies deviations between the two, which is useful for cross-calibration.
  3. Bluetooth Logging: Using a HC-05 or HC-06 module, the readings are sent to a smartphone App (Bluetooth Terminal), providing a wireless monitoring station for laboratories or home HVAC tuning.

ข้อมูล Frontmatter ดั้งเดิม 

title: "Measuring temperatures with LM35 and DS18B20"
description: "Temperature is measured from two different sensors and send data through bluetooth and a set of LEDs is lit according to average temperature"
author: "jomar"
category: "Sensors & Environment"
tags:
  - "environmental sensing"
  - "lights"
  - "communication"
  - "monitoring"
views: 17434
likes: 4
price: 1120
difficulty: "Easy"
components:
  - "1x HC-05 Bluetooth Module"
  - "1x LM35"
  - "1x Arduino Mega 2560"
  - "9x Resistor 221 ohm"
  - "1x Resistor 4.75k ohm"
  - "1x DS18B20 Programmable Resolution 1-Wire Digital Thermometer"
  - "1x Resistor 100 ohm"
  - "8x LED (generic)"
tools: []
apps:
  - "1x Bluetooth Terminal"
  - "1x Arduino IDE"
downloadableFiles:
  - "https://projects.arduinocontent.cc/e0f90759-5843-4fd0-a9b7-69492dea696e.ino"
  - "https://projects.arduinocontent.cc/e0f90759-5843-4fd0-a9b7-69492dea696e.ino"
documentationLinks: []
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seoDescription: "Learn to measure Temperature with LM35 and DS18B20 sensors, transmit data via Bluetooth, and control LEDs using Arduino."
videoLinks: []
heroImage: "https://cdn.jsdelivr.net/gh/bigboxthailand/arduino-assets@main/images/projects/measuring-temperatures-with-lm35-and-ds18b20-fee8f8_cover.jpg"
lang: "en"