ESP32 DS18B20 Dallas Temperature Sensor

🛠️ DS18B20 Dallas Temperature Sensor Troubleshooting

This guide outlines a systematic approach to troubleshoot and resolve common problems with the . Start by confirming that the hardware connections are correct, as wiring mistakes are the most frequent cause of issues. If you are sure the connections are correct, follow the below steps to debug common issues.

🌡️ One wire DS18B20 reading +85°C

❄️ DS18B20 Reading of -127°C

💻 Code Examples

Below you can find code examples of DS18B20 Dallas Temperature Sensor with ESP32 in several frameworks:

• Arduino IDE
• ESP-IDF
• ESPHome
• PlatformIO
• MicroPython

If you encounter issues while using the DS18B20 Dallas Temperature Sensor, check the Common Issues Troubleshooting Guide.

ESP32 DS18B20 Arduino IDE Code Example

Example in Arduino IDE

Fill in your main Arduino IDE sketch file with the following code to use the DS18B20 Dallas Temperature Sensor:

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

// Data wire is connected to GPIO4 (D2 on many boards)
#define ONE_WIRE_BUS 4

// Setup a oneWire instance to communicate with any OneWire devices
OneWire oneWire(ONE_WIRE_BUS);

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

void setup() {
  Serial.begin(115200);
  Serial.println("DS18B20 Temperature Sensor");

  // Start the DS18B20 sensor
  sensors.begin();
}

void loop() {
  // Request temperature readings from the sensor
  sensors.requestTemperatures();
  
  // Fetch and print the temperature
  float temperatureC = sensors.getTempCByIndex(0);
  Serial.print("Temperature: ");
  Serial.print(temperatureC);
  Serial.println("°C");

  // Delay for 2 seconds before taking the next reading
  delay(2000);
}

This Arduino sketch interfaces with the DS18B20 temperature sensor using the OneWire protocol. It reads temperature data and prints it to the Serial Monitor.

Library Requirement #

To use this code, install the required libraries:

1. OneWire Library

   • Allows communication with OneWire devices.
   • Install via Arduino Library Manager or manually from:
     🔗 OneWire Library

2. DallasTemperature Library

   • Simplifies interaction with DS18B20 sensors.
   • Install via Arduino Library Manager or from:
     🔗 DallasTemperature Library

Code Breakdown #

1. Setup OneWire Communication

   • ONE_WIRE_BUS (GPIO4) defines the data pin for DS18B20.
   • The OneWire instance is passed to DallasTemperature.

2. Initialization (setup())

   • Serial communication starts at 115200 baud.
   • sensors.begin() initializes the DS18B20 sensor.

3. Temperature Reading (loop())

   • sensors.requestTemperatures() fetches sensor data.
   • sensors.getTempCByIndex(0) retrieves the temperature in Celsius.
   • The value is printed to the Serial Monitor.

A 2-second delay ensures stable readings. 🚀

Connect your ESP32 to your computer via a USB cable, Ensure the correct Board and Port are selected under Tools, Click the "Upload" button in the Arduino IDE to compile and upload the code to your ESP32.

ESP32 DS18B20 ESP-IDF Code Example

Example in Espressif IoT Framework (ESP-IDF)

If you're using ESP-IDF to work with the DS18B20 Dallas Temperature Sensor, here's how you can set it up and read data from the sensor. Fill in this code in the main ESP-IDF file:

#include <stdio.h>
#include <string.h>
#include "esp_log.h"
#include "esp_err.h"
#include "ds18b20.h"
#include "onewire_bus.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

#define ONE_WIRE_GPIO    4   // Change this to your preferred GPIO pin
#define MAX_DS18B20      2   // Maximum number of DS18B20 sensors
#define DS18B20_CONVERSION_DELAY_MS 750  // Default conversion delay for 12-bit resolution

static const char *TAG = "DS18B20";

void app_main(void) {
    // Install the 1-Wire bus
    onewire_bus_handle_t bus = NULL;
    onewire_bus_config_t bus_config = {
        .bus_gpio_num = ONE_WIRE_GPIO,
    };

    onewire_bus_rmt_config_t rmt_config = {
        .max_rx_bytes = 10, // 1-byte ROM command + 8 bytes ROM number + 1 byte device command
    };

    ESP_ERROR_CHECK(onewire_new_bus_rmt(&bus_config, &rmt_config, &bus));

    int ds18b20_device_num = 0;
    ds18b20_device_handle_t ds18b20s[MAX_DS18B20];
    onewire_device_iter_handle_t iter = NULL;
    onewire_device_t next_onewire_device;
    esp_err_t search_result = ESP_OK;

    // Create 1-Wire device iterator to search for sensors
    ESP_ERROR_CHECK(onewire_new_device_iter(bus, &iter));
    ESP_LOGI(TAG, "Device iterator created, start searching...");

    do {
        search_result = onewire_device_iter_get_next(iter, &next_onewire_device);
        if (search_result == ESP_OK) {
            ds18b20_config_t ds_cfg = {};  // Initialize DS18B20 config

            // Check if the device is a DS18B20 sensor
            if (ds18b20_new_device(&next_onewire_device, &ds_cfg, &ds18b20s[ds18b20_device_num]) == ESP_OK) {
                ESP_LOGI(TAG, "Found DS18B20[%d], address: %016llX", ds18b20_device_num, next_onewire_device.address);
                ds18b20_device_num++;
            } else {
                ESP_LOGW(TAG, "Found unknown device, address: %016llX", next_onewire_device.address);
            }
        }
    } while (search_result != ESP_ERR_NOT_FOUND);

    ESP_ERROR_CHECK(onewire_del_device_iter(iter));
    ESP_LOGI(TAG, "Searching done, %d DS18B20 device(s) found", ds18b20_device_num);

    // Read and print temperature from each detected DS18B20 sensor
    while (1) {
        for (int i = 0; i < ds18b20_device_num; i++) {
            float temperature = 0.0;
            if (ds18b20_trigger_temperature_conversion(ds18b20s[i]) == ESP_OK) {
                vTaskDelay(pdMS_TO_TICKS(DS18B20_CONVERSION_DELAY_MS));  // Wait for conversion
                if (ds18b20_get_temperature(ds18b20s[i], &temperature) == ESP_OK) {
                    ESP_LOGI(TAG, "DS18B20[%d] Temperature: %.2f°C", i, temperature);
                } else {
                    ESP_LOGE(TAG, "Failed to get temperature from DS18B20[%d]", i);
                }
            } else {
                ESP_LOGE(TAG, "Failed to trigger temperature conversion for DS18B20[%d]", i);
            }
        }
        vTaskDelay(pdMS_TO_TICKS(2000));  // Wait 2 seconds before the next reading
    }
}

This ESP-IDF example demonstrates how to interface with the DS18B20 temperature sensor using OneWire communication on an ESP32.

Library Requirements #

To compile and run this code, you must install the required ESP-IDF components:

1. OneWire Bus Library

   • Handles OneWire communication on ESP32 using the RMT peripheral.
   • Install via ESP-IDF Component Manager:

     idf.py add-dependency "espressif/onewire_bus"
     

   • Or download manually:
     🔗 OneWire Bus Library

2. DS18B20 Driver

   • Provides functions to initialize and read data from DS18B20 sensors.
   • Install via ESP-IDF Component Manager:

     idf.py add-dependency "espressif/ds18b20"
     

   • Or download manually:
     🔗 DS18B20 Library

Code Breakdown #

1. Initialize OneWire Bus

   • ONE_WIRE_GPIO (GPIO4) is defined as the data pin.
   • onewire_new_bus_rmt() sets up OneWire communication using ESP32's RMT peripheral.

2. Search for DS18B20 Sensors

   • onewire_new_device_iter() scans for devices on the bus.
   • Detected DS18B20 sensors are stored in an array.

3. Reading Temperature

   • ds18b20_trigger_temperature_conversion() starts a measurement.
   • A 750ms delay ensures accurate readings at 12-bit resolution.
   • ds18b20_get_temperature() retrieves the temperature.
   • The result is logged using ESP_LOGI().

4. Continuous Monitoring

   • The code loops indefinitely, reading sensor data every 2 seconds.

Update the I2C pins (I2C_MASTER_SDA_IO and I2C_MASTER_SCL_IO) to match your ESP32 hardware setup, Use idf.py build to compile the project, Use idf.py flash to upload the code to your ESP32.

ESP32 DS18B20 ESPHome Code Example

Example in ESPHome (Home Assistant)

Fill in this configuration in your ESPHome YAML configuration file (example.yml) to integrate the DS18B20 Dallas Temperature Sensor

sensor: 
  - platform: dallas_temp
    address: 0x1234567812345628
    name: temperature
    update_interval: 120s

This ESPHome configuration integrates the Dallas Temperature Sensor (DS18B20) for OneWire communication.

Code Breakdown #

• The configuration defines a sensor with key attributes:
  • platform → Specifies the Dallas platform for DS18B20 sensors.
  • address → Unique hardware ID of the sensor.
  • name → Custom label for the sensor.
  • update_interval → Defines how often temperature readings are updated.

For detailed configuration options, refer to the official ESPHome documentation:
🔗 ESPHome Dallas Temperature Sensor

Upload this code to your ESP32 using the ESPHome dashboard or the esphome run command.

ESP32 DS18B20 PlatformIO Code Example

Example in PlatformIO Framework

For PlatformIO, make sure to configure the platformio.ini file with the appropriate environment and libraries, and then proceed with the code.

Configure platformio.ini

First, your platformio.ini should look like below. You might need to include some libraries as shown. Make sure to change the board to your ESP32:

[env:esp32]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
lib_deps =
    paulstoffregen/OneWire @ ^2.3.7
    milesburton/DallasTemperature @ ^3.11.0

ESP32 DS18B20 PlatformIO Example Code

Write this code in your PlatformIO project under the src/main.cpp file to use the DS18B20 Dallas Temperature Sensor:

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

// Data wire is connected to GPIO4
#define ONE_WIRE_BUS 4

// Create a oneWire instance to communicate with any OneWire devices
OneWire oneWire(ONE_WIRE_BUS);

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

void setup() {
    Serial.begin(115200);
    Serial.println("DS18B20 Temperature Sensor with PlatformIO");

    // Start the DS18B20 sensor
    sensors.begin();
}

void loop() {
    // Request temperature measurement
    sensors.requestTemperatures();

    // Get temperature in Celsius
    float temperatureC = sensors.getTempCByIndex(0);

    // Print the temperature to the serial monitor
    Serial.print("Temperature: ");
    Serial.print(temperatureC);
    Serial.println("°C");

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

• #include and #include import the required libraries for 1-Wire communication and DS18B20 sensor handling.
• #define ONE_WIRE_BUS 4 sets the GPIO pin connected to the DS18B20 data pin.
• The setup() function initializes serial communication and the DS18B20 sensor with sensors.begin().
• In the loop() function, sensors.requestTemperatures() requests a temperature measurement.
• sensors.getTempCByIndex(0) retrieves the temperature in Celsius, which is printed to the serial monitor using Serial.print().

Upload the code to your ESP32 using the PlatformIO "Upload" button in your IDE or the pio run --target upload command.

ESP32 DS18B20 MicroPython Code Example

Example in Micro Python Framework

Fill in this script in your MicroPython main.py file (main.py) to integrate the DS18B20 Dallas Temperature Sensor with your ESP32.

import machine
import onewire
import ds18x20
import time

# Define the GPIO pin where the DS18B20 data line is connected
ds_pin = machine.Pin(4)

# Create a OneWire object
ow = onewire.OneWire(ds_pin)

# Create a DS18X20 object
ds = ds18x20.DS18X20(ow)

# Scan for DS18B20 devices on the bus
roms = ds.scan()
print("Found DS18B20 devices:", roms)

while True:
    # Request temperature conversion
    ds.convert_temp()
    time.sleep(1)  # Wait for the conversion to complete

    # Read temperature from each device
    for rom in roms:
        temp = ds.read_temp(rom)
        print("Temperature:", temp, "°C")

    time.sleep(2)  # Delay before the next reading

• import machine, import onewire, and import ds18x20 are used to handle GPIO pins, 1-Wire protocol, and DS18B20 sensor operations respectively.
• ds_pin = machine.Pin(4) sets GPIO4 as the pin connected to the DS18B20 data line.
• The OneWire and DS18X20 objects are initialized to communicate with the sensor.
• ds.scan() searches for DS18B20 sensors connected to the bus and returns their ROM addresses.
• Inside a loop, ds.convert_temp() starts a temperature measurement, and ds.read_temp(rom) reads the temperature from each sensor.
• The temperature readings are printed to the console with print().

Upload this code to your ESP32 using a MicroPython-compatible IDE, such as Thonny, uPyCraft, or tools like ampy.