Week 8: Input Devices

Testing Temperature Sensor

I kept this week focused on testing the temperature sensor I'll be using in my final project. I used the BOJACK DS18B20 Temperature Sensor, which was $9 on Amazon and can measure temperatures in water - perfect for my Smart Aquarium.

About the DS18B20

After reading through the datasheet, I learned some key features about this sensor:

• Temperature Range: -55°C to +125°C (-67°F to +257°F)
• Accuracy: ±0.5°C from -10°C to +85°C
• Resolution: Programmable from 9 to 12 bits
• Conversion Time: 750ms maximum for 12-bit readings
• Power Supply: 3.0V to 5.5V operating range
• Communication: Uses 1-Wire protocol (only needs one data line)
• Special Features: Each sensor has a unique 64-bit serial code

Testing Process

I tested this using the PCB that I made for electronics/my final project. The sensor requires a pull-up resistor and can be powered by a 5V battery, making it perfect for initial testing.

Temperature readings from the sensor in the Serial Monitor

Code

Here's the simple test code I used:

#include 
#include 

// Data wire is connected to pin 2
#define ONE_WIRE_BUS 2

// Setup a oneWire instance
OneWire oneWire(ONE_WIRE_BUS);

// Pass oneWire reference to Dallas Temperature
DallasTemperature sensors(&oneWire);

void setup(void)
{
  Serial.begin(9600);
  sensors.begin();
}

void loop(void)
{ 
  sensors.requestTemperatures(); 
  
  Serial.print("Temperature is: ");
  Serial.println(sensors.getTempCByIndex(0));
  
  delay(1000);
}
    

Applications

The DS18B20 is particularly well-suited for aquarium use because:

• It's waterproof
• Has high accuracy (±0.5°C) in normal temperature ranges
• Can operate with "parasite power" if needed
• Allows multiple sensors on one wire (useful for monitoring different tank zones)

Reflection

This simple test was crucial for my final project development. Key learnings:

• The DS18B20 is waterproof and perfect for aquarium use
• It requires a pull-up resistor to work properly
• The sensor is quite accurate and responds quickly to temperature changes (tested by putting in a cup of water, and holding in my hand)
• Battery power works well for testing, but I'll probably use my laptop for stable power for the final project

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