USB Thermometer Python library

Overview

This project provides a Python 3 library for interfacing with DS18B20 temperature sensors via a USB-based 1-Wire interface. The library implements the 1-Wire protocol over a serial port, allowing you to discover connected sensors, read temperature measurements, configure sensor settings (precision, alarm thresholds), and perform low-level bit manipulations required for proper communication with the sensors.

Features

• Sensor Discovery: Detect all DS18B20 sensors on the 1-Wire bus.
• Temperature Reading: Continuously read sensor temperature values.
• Sensor Configuration: Write to and read from the sensor scratchpad, set measurement precision and alarm thresholds.
• Utilities: Functions for converting bit lists to hexadecimal strings/bytearrays and computing CRC8 checksums.
• Examples: Three comprehensive examples demonstrate:
  1. Discovering sensors and continuously reading their temperatures.
  2. Storing sensor data in an SQL database using SQLAlchemy.
  3. Configuring sensor settings (precision and alarm thresholds).

Project Structure

• wire.py
  Implements the USBThermometer class which manages communication with DS18B20 sensors via a serial port.

• sensors.py
  Contains the DS18B20 class that represents individual temperature sensors, handling their ROM codes, serial numbers, and configuration registers.

• utils.py
  Provides utility functions for bit manipulation, hexadecimal conversion, and CRC8 calculation.

• tests
  Unit tests for verifying the functionality of the library.

• examples
  Example scripts demonstrating different use cases:

  • example1.py: Discover sensors and continuously read temperatures until interrupted.
  • example2.py: Record sensor samples to a SQL database (SQLite or PostgreSQL) using SQLAlchemy.
  • example3.py: Configure sensor settings such as precision and alarm thresholds.

Installation

1. Clone the repository:

   git clone https://github.com/electromake/usb-thermometer-python.git
   cd usb-thermometer-python

2. Install required dependencies:

   pip install pyserial sqlalchemy
   # If you would like to run SQL example, run also:
   pip install sqlalchemy

Usage

Example 1: Continuous Temperature Reading

Discover all sensors and continuously read their temperatures until a keyboard interrupt (Ctrl+C) is detected.

python example1.py

Example 2: Storing Sensor Samples in a Database

Discover sensors and store temperature samples (with timestamps) in a SQL database. The database contains two tables: one for sensor details (ROM codes) and one for temperature samples.

python example2.py

Example 3: Configuring Sensor Settings

Configure sensor settings by adjusting measurement precision and alarm thresholds. The example shows how to write new settings to the sensor's scratchpad and verify them.

python example3.py

Testing

To run the unit tests, execute:

python -m unittest discover

More resources

• DS18B20 Datasheet
• 1-wire serial port implementation

Author

Electromake
https://electromake.pl/