dln2-i2c-wrapper 0.1.0

A Python library for DLN2 I2C adapters with an SMBus-style API. Originally developed for Pico USB IO Board.

DLN2 I2C Wrapper

A Python library for interfacing with DLN2 USB-to-I2C adapters with an SMBus-style API. It targets the Pico USB I/O Board firmware and packages the host-side I2C access layer as a standalone Python project.

Features

• SMBus-style API for common byte, word, and I2C block operations
• Low-level DLN2 USB client built on pyusb
• BME280 helper for chip ID, calibration, and measurement reads
• I2C scan and BME280 example scripts
• Pure Python, no compiled extension

Important Limitation

The firmware exposes separate DLN2 read and write commands. It does not expose a single combined repeated-start transaction through the USB protocol, so register reads are performed as:

1. Write register pointer
2. Start a separate read transaction

That works for many devices, but it is not identical to Linux i2c-dev combined transfers. i2c_rdwr() in this wrapper also executes messages sequentially for the same reason.

Installation

From source:

git clone https://github.com/syabyr/dln2_i2c_wrapper.git
cd dln2_i2c_wrapper
pip install .

For development:

pip install -e ".[dev]"

Quick Start

from dln2_i2c_wrapper import SMBus

with SMBus(1) as bus:
    device_addr = 0x50
    register = 0x00

    value = bus.read_byte_data(device_addr, register)
    print(hex(value))

    bus.write_byte_data(device_addr, register, 0x12)

BME280 Example

from dln2_i2c_wrapper import BME280

with BME280(bus=1, address=0x76) as sensor:
    print(hex(sensor.check_chip_id()))
    sensor.read_calibration()
    sensor.configure()
    print(sensor.read_measurements())

Command-Line Tools

dln2-i2c-test --help
dln2-i2c-scan --help
dln2-bme280-test --help

Use register-based probing when scanning devices that do not ACK a bare read, for example:

dln2-i2c-scan --register 0xD0 --read-len 1

Low-Level API

from dln2_i2c_wrapper import Dln2Usb, find_device

device = find_device()
client = Dln2Usb(device, debug=True)

client.i2c_enable()
client.i2c_write(0x50, b"\x00")
data = client.i2c_read(0x50, 4)
print(data.hex())
client.i2c_disable()
client.close()

Development

make test
make build