Adafruit Chainable DS18B20 Extender Breakout

DS18B20 wiring made easy!

by Liz Clark

published June 04, 2024, last edited January 21, 2025

posted in Adafruit Products Arduino Compatibles CircuitPython Breakout Boards STEMMA

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Beginner

Product guide

Overview

One of the perks of working at Adafruit is you get to request hardware - and you'll probably get fast turnaround! One of our adafruit.io developers requested "an easy way to chain DS18B20 sensors for testing with adafruit.io's Wippersnapper service" at 11:54am one Monday morning, and after a few back-and-forth's we came up with the Adafruit Chainable DS18B20 Extender Breakout. Bit of a mouth-full, but we're better engineers than marketers doncha-know.

While there is absolutely nothing stopping you from just wiring up DS18B20's directly to your microcontroller, these extender breakouts will make things just a lil bit easier. You can use JST 3-pin cables to chain the extenders, the soldered-on screw terminal blocks mean you can easily connect DS18B20's in TO-92 or cable style with just a screwdriver.

Each extender has a 4.7K signal pullup on board that can be disabled by cutting a trace, and a buffered signal LED that will let you know when there's data transmission on the 1-Wire line. When the red LED blinks, you know that data is going over the 1-wire line.

Please Note: This board doesn't come with a DS18B20 sensor itself; it's just an adapter-helper. You supply the sensor + a JST PH-compatible 3-pin cable.

Page last edited June 04, 2024

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Pinouts

This board doesn't come with a DS18B20 sensor itself; it's just an adapter-helper. You supply the sensor and a JST PH-compatible 3-pin cable.

DS18B20 Terminal Block

At the top edge of the board is a 1x3 terminal block. This block lets you connect a DS18B20 sensor to the breakout board.

V+ - the power connection for the DS18B20
Signal - the signal connection for the DS18B20 1-wire line
GND - the ground connection for the DS18B20

STEMMA JST PH Ports

On either side of the breakout is a STEMMA JST PH port. These two ports allow for chaining multiple breakouts together for use with 3-pin STEMMA JST PH cables. It has connections for:

GND - common ground for power and data. It is the black wire on the JST PH cable.
Vin - power input for the breakout. It is the red wire on the JST PH cable. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V microcontroller like Arduino, use 5V.
Sig - signal output from the DS18B20 to your microcontroller. It is the white wire on the JST PH cable.

Pullup Jumper

On the front of the board, in the center, is a jumper labeled PU. This is the Pullup Jumper for the breakout that is connected to the 4.7K signal pullup on board. You can cut the trace on this jumper to disconnect the signal pullup.

Signal LED and Jumper

Signal LED - in the bottom left corner on the front of the board is the signal LED, labeled Sig. It is the red LED. It will blink when there is data transmission on the 1-Wire line.
LED jumper - on the back of the board is a jumper for the signal LED. It is labeled SIG on the board silk. If you want to disable the signal LED, cut the trace on this jumper.

Power LED and Jumper

Power LED - in the bottom right corner on the front of the board is the power LED, labeled ON. It is the green LED.
LED jumper - on the back of the board is a jumper for the power LED. It is labeled ON on the board silk. If you want to disable the power LED, cut the trace on this jumper.

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CircuitPython

It's easy to use the Chainable DS18B20 Extender Breakout with CircuitPython and the Adafruit_CircuitPython_DS18X20 module. This module allows you to easily write Python code for reading the DS18B20 1-wire sensor.

You'll need a DS18B20 sensor to use this example with the breakout:

DS18B20 Digital temperature sensor next to a US quarter and above a resister.

DS18B20 Digital temperature sensor + extras

These 1-wire digital temperature sensors are fairly precise (±0.5°C over much of the range) and can give up to 12 bits of precision from the onboard digital-to-analog...

$3.95

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Waterproof 1-Wire DS18B20 Digital temperature sensor

This is a pre-wired and waterproofed (with heat shrink) version of a 1 Wire DS18B20 sensor. Handy for when you need to measure something far away, or in wet conditions. While the...

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CircuitPython Microcontroller Wiring

First wire up the DS18B20 sensor to the breakout exactly as follows. Then, connect the breakout to your microcontroller with a JST PH cable. The following is the breakout wired to a Feather RP2040 with a JST PH cable.

Breakout GND to DS18B20 ground (blue wire)
Breakout Signal to DS18B20 1-wire output (yellow wire)
Breakout V+ to DS18B20 VIN (red wire)
Board 3V to breakout JST PH VIN (red wire)
Board GND to breakout JST PH GND (black wire)
Board pin 5 to breakout JST PH Signal (white wire)

CircuitPython Usage

To use with CircuitPython, you need to first install the Adafruit_CircuitPython_DS18X20 library, and its dependencies, into the lib folder on your CIRCUITPY drive. Then you need to update code.py with the example script.

Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, and copy the entire lib folder and the code.py file to your CIRCUITPY drive.

Your CIRCUITPY/lib folder should contain the following folders and file:

adafruit_bus_device/
adafruit_onewire/
adafruit_ds18x20.mpy

Example Code

Once everything is saved to the CIRCUITPY drive, connect to the serial console to see the data printed out!

Download Project Bundle

Copy Code

# SPDX-FileCopyrightText: 2020 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# Simple demo of printing the temperature from the first found DS18x20 sensor every second.
# Author: Tony DiCola

# A 4.7Kohm pullup between DATA and POWER is REQUIRED!

import time

import board
from adafruit_onewire.bus import OneWireBus

from adafruit_ds18x20 import DS18X20

# Initialize one-wire bus on board pin D5.
ow_bus = OneWireBus(board.D5)

# Scan for sensors and grab the first one found.
ds18 = DS18X20(ow_bus, ow_bus.scan()[0])

# Main loop to print the temperature every second.
while True:
    print(f"Temperature: {ds18.temperature:0.3f}C")
    time.sleep(1.0)

# SPDX-FileCopyrightText: 2020 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# Simple demo of printing the temperature from the first found DS18x20 sensor every second.
# Author: Tony DiCola

# A 4.7Kohm pullup between DATA and POWER is REQUIRED!

import time

import board
from adafruit_onewire.bus import OneWireBus

from adafruit_ds18x20 import DS18X20

# Initialize one-wire bus on board pin D5.
ow_bus = OneWireBus(board.D5)

# Scan for sensors and grab the first one found.
ds18 = DS18X20(ow_bus, ow_bus.scan()[0])

# Main loop to print the temperature every second.
while True:
    print(f"Temperature: {ds18.temperature:0.3f}C")
    time.sleep(1.0)

In the code, the 1-wire bus is instantiated on pin 5. A scan is performed for the sensor and once it is found, the loop begins. In the loop, the temperature reading is printed to the serial console every second.

Multiple Sensors

What makes this breakout special though is right in its name: you can chain multiple DS18B20 sensors together! To do this, you'll wire up multiple breakouts with DS18B20 sensors to your microcontroller. Then, you'll scan for each sensors' ROM address. After updating the code with their addresses, you can read multiple sensors at once.

Each breakout will be wired to a DS18B20 sensor with its terminal block:

Breakout GND to DS18B20 ground (blue wire)
Breakout Signal to DS18B20 1-wire output (yellow wire)
Breakout V+ to DS18B20 VIN (red wire)

The breakouts will be daisy chained together via their JST PH cables. The final breakout in the chain will be connected to the Feather:

Board 3V to breakout JST PH VIN (red wire)
Board GND to breakout JST PH GND (black wire)
Board pin 5 to breakout JST PH Signal (white wire)

You can determine the ROM address for each sensor using this code snippet:

Download File

Copy Code

import board
from adafruit_onewire.bus import OneWireBus, OneWireAddress

ow_bus = OneWireBus(board.D5)
for device in ow_bus.scan():
	print(device.rom)

import board
from adafruit_onewire.bus import OneWireBus, OneWireAddress

ow_bus = OneWireBus(board.D5)
for device in ow_bus.scan():
	print(device.rom)

The ROM addresses will print to the serial console:

You need to update the code with the ROM addresses for your sensors!

After noting the ROM addresses, you can update the multiple DS18B20 example code with your sensors' addresses. Once everything is saved to the CIRCUITPY drive, connect to the serial console to see the data printed out!

Download Project Bundle

Copy Code

# SPDX-FileCopyrightText: 2020 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# Example of specifying multiple sensors using explicit ROM codes.
# These ROM codes need to be determined ahead of time. Use `ow_bus.scan()`.
#
# (1) Connect one sensor at a time
# (2) Use `ow_bus.scan()[0].rom` to determine ROM code
# (3) Use ROM code to specify sensors (see this example)

import time

import board
from adafruit_onewire.bus import OneWireAddress, OneWireBus

from adafruit_ds18x20 import DS18X20

# !!!! REPLACE THESE WITH ROM CODES FOR YOUR SENSORS !!!!
ROM1 = b"(\xbb\xfcv\x08\x00\x00\xe2"
ROM2 = b"(\xb3t\xd3\x08\x00\x00\x9e"
ROM3 = b"(8`\xd4\x08\x00\x00i"
# !!!! REPLACE THESE WITH ROM CODES FOR YOUR SENSORS !!!!

# Initialize one-wire bus on board pin D5.
ow_bus = OneWireBus(board.D5)

# Uncomment this to get a listing of currently attached ROMs
# for device in ow_bus.scan():
#     print(device.rom)

# Use pre-determined ROM codes for each sensors
temp1 = DS18X20(ow_bus, OneWireAddress(ROM1))
temp2 = DS18X20(ow_bus, OneWireAddress(ROM2))
temp3 = DS18X20(ow_bus, OneWireAddress(ROM3))

# Main loop to print the temperatures every second.
while True:
    print(f"Temperature 1 = {temp1.temperature}")
    print(f"Temperature 2 = {temp2.temperature}")
    print(f"Temperature 3 = {temp3.temperature}")
    print("-" * 20)
    time.sleep(1)

# SPDX-FileCopyrightText: 2020 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# Example of specifying multiple sensors using explicit ROM codes.
# These ROM codes need to be determined ahead of time. Use `ow_bus.scan()`.
#
# (1) Connect one sensor at a time
# (2) Use `ow_bus.scan()[0].rom` to determine ROM code
# (3) Use ROM code to specify sensors (see this example)

import time

import board
from adafruit_onewire.bus import OneWireAddress, OneWireBus

from adafruit_ds18x20 import DS18X20

# !!!! REPLACE THESE WITH ROM CODES FOR YOUR SENSORS !!!!
ROM1 = b"(\xbb\xfcv\x08\x00\x00\xe2"
ROM2 = b"(\xb3t\xd3\x08\x00\x00\x9e"
ROM3 = b"(8`\xd4\x08\x00\x00i"
# !!!! REPLACE THESE WITH ROM CODES FOR YOUR SENSORS !!!!

# Initialize one-wire bus on board pin D5.
ow_bus = OneWireBus(board.D5)

# Uncomment this to get a listing of currently attached ROMs
# for device in ow_bus.scan():
#     print(device.rom)

# Use pre-determined ROM codes for each sensors
temp1 = DS18X20(ow_bus, OneWireAddress(ROM1))
temp2 = DS18X20(ow_bus, OneWireAddress(ROM2))
temp3 = DS18X20(ow_bus, OneWireAddress(ROM3))

# Main loop to print the temperatures every second.
while True:
    print(f"Temperature 1 = {temp1.temperature}")
    print(f"Temperature 2 = {temp2.temperature}")
    print(f"Temperature 3 = {temp3.temperature}")
    print("-" * 20)
    time.sleep(1)

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Arduino

Using the Chainable DS18B20 Extender Breakout with Arduino involves wiring up the breakout to your Arduino-compatible microcontroller with a DS18B20 sensor, installing the Dallas Temperature Control Library library, and running the provided example code.

DS18B20 Digital temperature sensor + extras

These 1-wire digital temperature sensors are fairly precise (±0.5°C over much of the range) and can give up to 12 bits of precision from the onboard digital-to-analog...

$3.95

In Stock

Add to Cart

Waterproof 1-Wire DS18B20 Digital temperature sensor

This is a pre-wired and waterproofed (with heat shrink) version of a 1 Wire DS18B20 sensor. Handy for when you need to measure something far away, or in wet conditions. While the...

$9.95

In Stock

Add to Cart

Wiring

Wire as shown for a 5V board like an Uno. If you are using a 3V board, like an Adafruit Feather, wire the board's 3V pin to the breakout VIN.

Here is an Adafruit Metro wired up to the breakout with a DS18B20 sensor:

Breakout GND to DS18B20 ground (blue wire)
Breakout Signal to DS18B20 1-wire output (yellow wire)
Breakout V+ to DS18B20 VIN (red wire)
Board 3V to breakout JST PH VIN (red wire)
Board GND to breakout JST PH GND (black wire)
Board pin 2 to breakout JST PH Signal (white wire)

Library Installation

You can install the Dallas Temperature Control Library library for Arduino using the Library Manager in the Arduino IDE.

Click the Manage Libraries ... menu item, search for DS18B20, and select the DallasTemperature library:

If asked about dependencies, click "Install all".

If the "Dependencies" window does not come up, then you already have the dependencies installed.

If the dependencies are already installed, you must make sure you update them through the Arduino Library Manager before loading the example!

Example Code

Open the Simple example in the DallasTemperature library by going to File - Examples - DallasTemperature - Simple.

Upload the sketch to your board and open up the Serial Monitor (Tools -> Serial Monitor) at 115200 baud. You'll see the temperature reading from your attached DS18B20 sensor print to the Serial Monitor.

Multiple Sensors

What makes this breakout special though is right in its name: you can chain multiple DS18B20 sensors together! To do this, you'll wire up multiple breakouts with DS18B20 sensors to your microcontroller and then upload the Multiple example from the Arduino Library for Maxim Temperature Integrated Circuits library.

Each breakout will be wired to a DS18B20 sensor with its terminal block:

Breakout GND to DS18B20 ground (blue wire)
Breakout Signal to DS18B20 1-wire output (yellow wire)
Breakout V+ to DS18B20 VIN (red wire)

The breakouts will be daisy chained together via their JST PH cables. The final breakout in the chain will be connected to the microcontroller:

Board 3V to breakout JST PH VIN (red wire)
Board GND to breakout JST PH GND (black wire)
Board pin 2 to breakout JST PH Signal (white wire)

Open the Multiple example in the DallasTemperature library by going to File - Examples - DallasTemperature - Multiple.

Upload the sketch to your board and open up the Serial Monitor (Tools -> Serial Monitor) at 115200 baud. You'll see the temperature readings from your attached DS18B20 sensors print to the Serial Monitor.