esp32-ds18b20-example

Introduction

This is an example application for the Maxim Integrated DS18B20 Programmable Resolution 1-Wire Digital Thermometer device.

It supports a single or multiple devices on the same 1-Wire bus.

It is written and tested for v3.3 of the ESP-IDF environment, using the xtensa-esp32-elf toolchain (gcc version 5.2.0, crosstool-ng-1.22.0-80-g6c4433a).

Ensure that submodules are cloned:

$ git clone --recursive https://github.com/DavidAntliff/esp32-ds18b20-example.git

Build the application with:

$ cd esp32-ds18b20-example
$ idf.py menuconfig    # set your serial configuration and the 1-Wire GPIO - see below
$ idf.py build
$ idf.py -p (PORT) flash monitor

The program should detect your connected devices and periodically obtain temperature readings from them, displaying them on the console.

Dependencies

This application makes use of the following components (included as submodules):

• components/esp32-owb
• components/esp32-ds18b20

Hardware

To run this example, connect one or more DS18B20 devices to a single GPIO on the ESP32. Use the recommended pull-up resistor of 4.7 KOhms, connected to the 3.3V supply.

idf.py menuconfig can be used to set the 1-Wire GPIO.

If you have several devices and see occasional CRC errors, consider using a 2.2 kOhm pull-up resistor instead. Also consider adding decoupling capacitors between the sensor supply voltage and ground, as close to each sensor as possible.

Features

This example provides:

• External power supply mode.
• Static (stack-based) or dynamic (malloc-based) memory model examples.
• No global variables.
• Device search.
• Addressing optimisation for a single (solo) device on a bus.
• CRC checks on ROM code and temperature data.
• Programmable temperature measurement resolution (9, 10, 11 or 12-bit resolution).
• Temperature conversion and retrieval.
• Simultaneous conversion across multiple devices.

Source Code

The source is available from GitHub.

License

The code in this project is licensed under the MIT license - see LICENSE for details.

Links

• DS18B20 Datasheet
• Espressif IoT Development Framework for ESP32

Acknowledgements

"1-Wire" is a registered trademark of Maxim Integrated.