How to Use Chainable DS18B20 extender breakout: Examples, Pinouts, and Specs

The Adafruit 5971 - DS18B20 Extender Breakout is a specialized breakout board designed to enhance the functionality of the DS18B20 digital temperature sensor. This board allows multiple DS18B20 sensors to be connected in a daisy-chain configuration, simplifying wiring and enabling scalable temperature sensing solutions. It is ideal for projects requiring multiple temperature readings over a single data line, such as environmental monitoring, industrial automation, and smart home systems.

• Multi-point temperature monitoring in HVAC systems
• Data logging for weather stations
• Industrial process control
• Smart agriculture and greenhouse monitoring
• IoT-based temperature sensing networks

The following table outlines the key technical details of the Adafruit 5971 - DS18B20 Extender Breakout:

The breakout board features a simple pinout for easy integration. Below is the pin configuration:

1. Power the Breakout Board: Connect the VIN pin to a 3.3V or 5V power source and the GND pin to ground.
2. Connect the Data Line:
   • Attach the DATA_IN pin to the 1-Wire data pin of your microcontroller (e.g., Arduino).
   • If chaining multiple boards, connect the DATA_OUT pin of the first board to the DATA_IN pin of the next board.
3. Attach DS18B20 Sensors: Plug the DS18B20 sensors into the breakout board's 3-pin connector.
4. Pull-Up Resistor: Ensure a 4.7kΩ pull-up resistor is connected between the data line and the power supply to stabilize the 1-Wire communication.

• Power Supply: Ensure the power supply voltage matches the requirements of both the breakout board and the DS18B20 sensors.
• Cable Length: Minimize cable length to reduce signal degradation, especially when chaining multiple boards.
• Sensor Addressing: Each DS18B20 sensor has a unique 64-bit address. Use this address to differentiate between sensors in your code.
• Environmental Protection: If used in harsh environments, protect the sensors and breakout boards with waterproof enclosures.

Below is an example of how to use the Adafruit 5971 - DS18B20 Extender Breakout with an Arduino UNO:

#include <OneWire.h>
#include <DallasTemperature.h>

// Define the 1-Wire bus pin
#define ONE_WIRE_BUS 2

// Create a OneWire instance to communicate with the DS18B20 sensors
OneWire oneWire(ONE_WIRE_BUS);

// Pass the OneWire reference to DallasTemperature library
DallasTemperature sensors(&oneWire);

void setup() {
  Serial.begin(9600);
  Serial.println("DS18B20 Extender Breakout Example");

  // Start the DallasTemperature library
  sensors.begin();
}

void loop() {
  Serial.println("Requesting temperatures...");
  
  // Request temperature readings from all sensors on the bus
  sensors.requestTemperatures();

  // Print the temperature of each sensor
  for (int i = 0; i < sensors.getDeviceCount(); i++) {
    float tempC = sensors.getTempCByIndex(i);
    Serial.print("Sensor ");
    Serial.print(i);
    Serial.print(": ");
    Serial.print(tempC);
    Serial.println(" °C");
  }

  // Wait 2 seconds before the next reading
  delay(2000);
}

1. No Temperature Readings:

   • Ensure the pull-up resistor (4.7kΩ) is properly connected between the data line and the power supply.
   • Verify that the sensors are securely connected to the breakout board.
   • Check the wiring for loose or incorrect connections.

2. Inconsistent Readings:

   • Reduce the length of the data line to minimize signal degradation.
   • Ensure the power supply is stable and within the specified voltage range.

3. Unable to Detect All Sensors:

   • Verify that each sensor is functioning correctly by testing them individually.
   • Ensure the total number of sensors does not exceed the 1-Wire bus limitations.

Q: Can I use this breakout board with other 1-Wire sensors?
A: This breakout board is specifically designed for DS18B20 sensors. Compatibility with other 1-Wire sensors is not guaranteed.

Q: How many sensors can I chain together?
A: The number of sensors is limited by the 1-Wire bus constraints, which depend on factors such as cable length, power supply, and pull-up resistor value. Typically, up to 10 sensors can be chained reliably.

Q: Do I need a separate pull-up resistor for each breakout board?
A: No, a single 4.7kΩ pull-up resistor on the data line is sufficient for the entire chain.

Q: Can I use this breakout board with a 3.3V microcontroller?
A: Yes, the breakout board supports both 3.3V and 5V logic levels, making it compatible with a wide range of microcontrollers.