PCF8574 WebApp

This is a Python library designed to be able to easily control your PCF8574 I/O expanders over a Web interface. The Library is based on the pcf8574_interface library, which extends the functionality of the original pcf8574 library with some useful features.

Features

• Display current I/O states: The web interface is able to display the current states of your PCF8574 I/O expanders.
• Override I/O states: You can override the current I/O states of your PCF8574 I/O expanders to test your hardware and software without changing the actual states.
• Default Web interface: The Default Web interface provides an overview of all connected PCF8574 I/O expanders and their current states.
• Custom Routes: You can create custom routes with custom templates to display only specific I/O pins.

Installation

You can install the library with the following command:

pip install pcf8574_webapp

Usage

Default Web Interface

The default web interface is automatically available at http://0.0.0.0:5000/.

Starting the WebApp

To start the web application, you can use the following code snippet:

from pcf8574_interface import PCF8574Interface, IoPortType, PCF8574Pool
from pcf8574_webapp import PCF8574WebApp

from uvicorn import Config, Server

pool = PCF8574Pool()

# Create a few interface instances
pcf1 = PCF8574Interface(i2c_bus_no=1, address=0x20, io_type=IoPortType.OUT)
pcf2 = PCF8574Interface(i2c_bus_no=1, address=0x21, io_type=IoPortType.IN)

# Add them to the pool
pool.add_port(pcf1)
pool.add_port(pcf2)

fastapi_webapp = PCF8574WebApp(pool)
pool.set_api(fastapi_webapp.get_notifier())
config = Config(app=fastapi_webapp.get_app(), host="0.0.0.0", port=5000, log_level="info")
server = Server(config)
server.run()
# or if you want to run it asynchronously:
# try:
#     await server.serve()
# except KeyboardInterrupt:
#     print("WebApp server stopped.")

Custom Routes

You can create custom routes to display specific I/O pins or groups of pins. For example, to create a route that displays all input ports, you can use the following code snippet after the instantiation of PCF8574WebApp:

fastapi_webapp.add_route(
    "/inputs",
    "index.html",
    {
        "inputs": pool.get_ports_by_type(IoPortType.IN),
    }
)

Custom Templates

If you want to use custom templates, you need to register the directory containing your custom templates.

custom_pins.html

{% extends "base.html" %}
{% block title %}Custom Template{% endblock %}

{% block content %}
    ...
    {% with resource=custom_ports %}
        {% include '_table.html' %}
    {% endwith %}
    ...
{% endblock %}

from pathlib import Path

fastapi_webapp.add_template_directory(Path(__file__).resolve().parent / "custom_templates")
fastapi_webapp.add_route(
    "/custom_ports",
    "custom_ports.html",
    {
        "custom_ports": (pool.get_port(1, 0x20), pool.get_port(1, 0x21))
    }
)