1-wire-digital-temp-sensor-with-raspberry-pi.md

Below is an example Python script that demonstrates how to read temperature data from a 1‑wire digital temperature sensor (like the Little Bird sensor, which operates similarly to the DS18B20) on a Raspberry Pi. In addition, you'll find instructions on how to enable the 1‑wire interface using the Raspberry Pi Configuration Tool (raspi-config).

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Step 1. Enable the 1‑Wire Interface

Using raspi-config

1. Open Terminal:
   Open a terminal on your Raspberry Pi.

2. Run Raspberry Pi Configuration Tool:

   sudo raspi-config

3. Navigate to Interfacing Options:

   • Select Interfacing Options.
   • Then choose 1-Wire.
   • When prompted, select Yes to enable the 1‑wire interface.

4. Finish and Reboot:
   Exit raspi-config and reboot your Raspberry Pi for the changes to take effect:

   sudo reboot

Alternative Method: Editing /boot/config.txt

If you prefer, you can manually enable the interface by adding the following line to your /boot/config.txt file:

dtoverlay=w1-gpio

After editing, reboot your Raspberry Pi.

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Step 2. Example Python Code

Below is an example Python script that reads temperature data from your sensor. The script loads the required kernel modules (w1-gpio and w1-therm), locates the sensor device directory, and parses the temperature value from the sensor’s data file.

#!/usr/bin/env python3
import os
import glob
import time

# Load the necessary kernel modules (optional if already loaded at boot)
os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')

# Base directory where 1-wire devices are listed
base_dir = '/sys/bus/w1/devices/'

# Find the device folder for our sensor (typically starts with '28-')
device_folders = glob.glob(base_dir + '28*')
if not device_folders:
    raise RuntimeError("Could not find a 1-wire device. Ensure your sensor is connected and 1-wire is enabled.")
device_folder = device_folders[0]
device_file = device_folder + '/w1_slave'

def read_raw_data():
    """Read the raw data from the sensor file."""
    with open(device_file, 'r') as f:
        lines = f.readlines()
    return lines

def read_temperature():
    """Parse the raw sensor data to extract temperature in Celsius and Fahrenheit."""
    lines = read_raw_data()
    
    # Wait until the sensor output is valid (first line ends with 'YES')
    while lines[0].strip()[-3:] != 'YES':
        time.sleep(0.2)
        lines = read_raw_data()

    # Extract the temperature value from the second line after the 't=' marker
    equals_pos = lines[1].find('t=')
    if equals_pos != -1:
        temp_string = lines[1][equals_pos + 2:]
        temp_c = float(temp_string) / 1000.0  # Convert to Celsius
        temp_f = temp_c * 9.0 / 5.0 + 32.0      # Convert to Fahrenheit
        return temp_c, temp_f
    else:
        raise RuntimeError("Couldn't read temperature value.")

if __name__ == '__main__':
    try:
        while True:
            temp_c, temp_f = read_temperature()
            print("Temperature: {:.3f}°C / {:.3f}°F".format(temp_c, temp_f))
            time.sleep(1)  # Wait 1 second before the next reading
    except KeyboardInterrupt:
        print("Exiting...")

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How It Works

1. Enabling 1‑Wire:

   • The instructions above guide you through enabling the 1‑wire interface via raspi-config (or by editing /boot/config.txt), ensuring the necessary kernel modules are available.

2. Loading Kernel Modules:

   • The script uses os.system() to load w1-gpio and w1-therm. If these modules are already loaded via the boot configuration, these commands are optional.

3. Locating the Sensor:

   • The sensor is recognized as a device folder in /sys/bus/w1/devices/ with an identifier starting with 28-. The script uses the glob module to find this directory.

4. Reading and Parsing Sensor Data:

   • The sensor outputs data to a file called w1_slave. The script reads this file, verifies that the first line ends with YES (indicating a valid reading), and extracts the temperature (provided in thousandths of a degree Celsius), converting it to both Celsius and Fahrenheit.

5. Continuous Readings:

   • The script runs in an infinite loop, printing the temperature every second until you stop the program (e.g., by pressing Ctrl+C).

This example should help you get started with using the Little Bird 1‑Wire Digital Temperature Sensor on your Raspberry Pi for environmental sensing, data logging, and IoT applications.