Android USB Serial Support in pyserial with Chaquopy Integration

[Qlexio]

Description

This PR enhances pyserial to support serial connections on Android via Chaquopy and usb-serial-for-android. It enables pyserial to work in Android environments, specifically for firmware flashing tools like esptool.py.

Motivation

Android firmware developers need reliable serial connections to flash devices like ESP32/ESP8266 from Android apps. esptool.py, which uses pyserial, faces compatibility issues on Android. This PR integrates usb-serial-for-android to address this.

Context

Addresses the following issues: #192, #428, #603, #762

Implementation

1. Chaquopy enables Python within Android, allowing pyserial to run.

2. usb-serial-for-android is integrated to provide Android-compatible serial drivers.

3. Example Usage: Call pyserial-based functions from Android using Kotlin.

   val python = Python.getInstance()
   val pyScript = python.getModule("upload_firmware")
   pyScript.callAttr("upload_firmware", this)
   

4. Python Script: Sample upload_firmware.py for ESP32-S3 flashing via esptool.py.

import os
import esptool
from serial.android import set_android_context
from os.path import dirname, join
from android.content import Context



def upload_firmware(context:Context):
    firmware_path = (join(dirname(__file__), 'ESP32S3-Firmware.bin'))

    if not os.path.isfile(firmware_path):
        raise Exception(f"Firmware file not found at {firmware_path}")

    print("Starting firmware upload...")
    set_android_context(context)

    esptool.main(['--chip', 'esp32s3', '--baud', '230400', 'write_flash', '-z', '0x10000', firmware_path])

Testing

Demo App: https://github.com/xCarlost/FirmwareFlasher
This app flashes a test firmware onto an ESP32-S3.

@mcuee, @bdureau

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This issue has been cloned from: pyserial#780