Enable user to pass platform's native I2C object to `get_i2c_driver()`

[sfe-SparkFro]

If a user wants to use a non-default I2C bus, the current implementation requires the user to provide arguments for the platform's native I2C implementation:

################################################################################
# Qwiic I2C Driver
################################################################################

import qwiic_i2c

# MicroPython and CircuitPython
i2c_driver = qwiic_i2c.get_i2c_driver(sda = 0, scl = 1)

# Linux
i2c_driver = qwiic_i2c.get_i2c_driver(iBus = 0)

################################################################################
# Qwiic Device
################################################################################

# Pass driver to the Qwiic device constructor
import qwiic_device
my_device = qwiic_device.QwiicDevice(i2c_driver = i2c_driver)

However, it would be beneficial to allow the user to provide a platform's native I2C object that's already pre-configured:

################################################################################
# Platform I2C Object
################################################################################

# MicroPython
import machine
native_i2c = machine.I2C(sda = 0, scl = 1)
native_i2c = machine.SoftI2C(sda = 0, scl = 1)

# CircuitPython
import busio
native_i2c = busio.I2C(sda = 0, scl = 1)

# Linux
import smbus2
native_i2c = smbus2.SMBus(iBus = 0)

################################################################################
# Qwiic I2C Driver
################################################################################

# All platforms
import qwiic_i2c
i2c_driver = qwiic_i2c.get_i2c_driver(native_i2c)

################################################################################
# Qwiic Device
################################################################################

# Pass driver to the Qwiic device constructor
import qwiic_device
my_device = qwiic_device.QwiicDevice(i2c_driver = i2c_driver)

One major benefit is the ability to use a SoftI2C object in MicroPython, which is current impossible.

---

This is bigger scope, but it would be nice if all the device drivers could also accept the native_i2c object:

################################################################################
# Platform I2C Object
################################################################################

# MicroPython
import machine
native_i2c = machine.I2C(sda = 0, scl = 1)
native_i2c = machine.SoftI2C(sda = 0, scl = 1)

# CircuitPython
import busio
native_i2c = busio.I2C(sda = 0, scl = 1)

# Linux
import smbus2
native_i2c = smbus2.SMBus(iBus = 0)

################################################################################
# Qwiic Device
################################################################################

# Pass native I2C object to the Qwiic device constructor
import qwiic_device
my_device = qwiic_device.QwiicDevice(i2c_driver = native_i2c)

The device driver constructors would have to check isinstance(i2c_driver, qwiic_i2c.I2CDriver):

 class QwiicDevice():
     def __init__(self, i2c_driver, ...):
         # Load the I2C driver if one isn't provided
         if i2c_driver is None:
             self._i2c = qwiic_i2c.getI2CDriver()
             if self._i2c is None:
                 print("Unable to load I2C driver for this platform.")
                 return
+        # Load the I2C driver if native I2C object is provided
+        elif not isinstance(i2c_driver, qwiic_i2c.I2CDriver):
+            self._i2c = qwiic_i2c.getI2CDriver(i2c_driver)
         else:
             self._i2c = i2c_driver      

This would eliminate the need for users to call i2c_driver = qwiic_i2c.get_i2c_driver(...) (which they are likely unfamiliar with) in favor of only having to use the platform's native I2C object (which they are likely already familiar with).

[gigapod]

First - love the idea of being able to pass in a native I2C object and having that used - returned wrapped in the frameworks I2C class for that platform.

A couple thoughts come to mind ...

• Have the qwiic_i2c.getI2CDriver() method also accept the native driver as an argument. The underlying system would do the argument validation to determine what to do (return default, create a object based on SDL & SDA, use the passed in native object), but it's doable. In this mode, the QwiicDevice constructor/init method would just pass in any args it recives to the underlying getI2CDriver() ... -- so driver code is kept fairly simple/ stays the same.
• A definition of the "current" I2C bus object would be needed. Or maybe it's just the "default". Once you have multiple bus objects in use, the use heuristics need definition.

-K