Introduction¶

Classes for use in communicating with devices on a 1-Wire bus.

Dependencies¶

This driver depends on:

Adafruit CircuitPython

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle.

Usage Example¶

import board
from adafruit_onewire.bus import OneWireBus
ow_bus = OneWireBus(board.D2)
devices = ow_bus.scan()
for d in devices:
    print("ROM={}\tFamily=0x{:02x}".format(d.rom, d.family_code))

Contributing¶

Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.

Building locally¶

To build this library locally you’ll need to install the circuitpython-build-tools package.

python3 -m venv .env
source .env/bin/activate
pip install circuitpython-build-tools

Once installed, make sure you are in the virtual environment:

source .env/bin/activate

Then run the build:

circuitpython-build-bundles --filename_prefix adafruit-circuitpython-onewire --library_location .

Sphinx documentation¶

Sphinx is used to build the documentation based on rST files and comments in the code. First, install dependencies (feel free to reuse the virtual environment from above):

python3 -m venv .env
source .env/bin/activate
pip install Sphinx sphinx-rtd-theme

Now, once you have the virtual environment activated:

cd docs
sphinx-build -E -W -b html . _build/html

This will output the documentation to docs/_build/html. Open the index.html in your browser to view them. It will also (due to -W) error out on any warning like Travis will. This is a good way to locally verify it will pass.

Table of Contents¶

Simple test¶

Ensure your device works with this simple test.

examples/onewire_demo.py¶

import board
from adafruit_onewire.bus import OneWireBus

# Create the 1-Wire Bus
# Use whatever pin you've connected to on your board
ow_bus = OneWireBus(board.D2)

# Reset and check for presence pulse.
# This is basically - "is there anything out there?"
print("Resetting bus...", end='')
if ow_bus.reset():
    print("OK.")
else:
    raise RuntimeError("Nothing found on bus.")

# Run a scan to get all of the device ROM values
print("Scanning for devices...", end='')
devices = ow_bus.scan()
print("OK.")
print("Found {} device(s).".format(len(devices)))

# For each device found, print out some info
for i, d in enumerate(devices):
    print("Device {:>3}".format(i))
    print("\tSerial Number = ", end='')
    for byte in d.serial_number:
        print("0x{:02x} ".format(byte), end='')
    print("\n\tFamily = 0x{:02x}".format(d.family_code))

# Usage beyond this is device specific. See a CircuitPython library for a 1-Wire
# device for examples and how OneWireDevice is used.

`adafruit_onewire.bus`¶

Provide access to a 1-Wire bus.

Author(s): Carter Nelson

class adafruit_onewire.bus.OneWireAddress(rom)[source]¶

A class to represent a 1-Wire address.

crc¶: The 8 bit CRC.

family_code¶: The 8 bit family code.

rom¶: The unique 64 bit ROM code.

serial_number¶: The 48 bit serial number.

class adafruit_onewire.bus.OneWireBus(pin)[source]¶

A class to represent a 1-Wire bus.

static crc8(data)[source]¶

Perform the 1-Wire CRC check on the provided data.

Parameters:	data (bytearray) – 8 byte array representing 64 bit ROM code

maximum_devices¶: The maximum number of devices the bus will scan for. Valid range is 1 to 255. It is an error to have more devices on the bus than this number. Having less is OK.

readinto(buf, *, start=0, end=None)[source]¶

Read into buf from the device. The number of bytes read will be the length of buf.

If start or end is provided, then the buffer will be sliced as if buf[start:end]. This will not cause an allocation like buf[start:end] will so it saves memory.

Parameters:	buf (bytearray) – buffer to write into start (int) – Index to start writing at end (int) – Index to write up to but not include

reset(required=False)[source]¶

Perform a reset and check for presence pulse.

Parameters:	required (bool) – require presence pulse

scan()[source]¶: Scan for devices on the bus and return a list of addresses.

write(buf, *, start=0, end=None)[source]¶

Write the bytes from buf to the device.

If start or end is provided, then the buffer will be sliced as if buffer[start:end]. This will not cause an allocation like buffer[start:end] will so it saves memory.

Parameters:	buf (bytearray) – buffer containing the bytes to write start (int) – Index to start writing from end (int) – Index to read up to but not include

exception adafruit_onewire.bus.OneWireError[source]¶: A class to represent a 1-Wire exception.

`adafruit_onewire.device`¶

Provides access to a single device on the 1-Wire bus.

Author(s): Carter Nelson

class adafruit_onewire.device.OneWireDevice(bus, address)[source]¶

A class to represent a single device on the 1-Wire bus.