Importing The Package And Instantiating The Library

Importing

To import this package, the standard import string is:

from tmx_pico_aio import tmx_pico_aio

Here is an example of instantiating the library and blinking the board LED until the user enters Control-C to end the application.




import asyncio
import sys

from tmx_pico_aio import tmx_pico_aio

"""
Setup a pin for digital output 
and toggle the pin 5 times.
"""

# some globals
DIGITAL_PIN = 25  # the board LED


async def blink(my_board, pin):
    # Set the DIGITAL_PIN as an output pin
    # set the pin mode
    await my_board.set_pin_mode_digital_output(pin)

    # toggle the pin 4 times and exit
    for x in range(4):
        print('ON')
        await my_board.digital_write(pin, 1)
        await asyncio.sleep(1)
        print('OFF')
        await my_board.digital_write(pin, 0)
        await asyncio.sleep(1)


# get the event loop
loop = asyncio.get_event_loop()
try:
    board = tmx_pico_aio.TmxPicoAio()
except KeyboardInterrupt:
    sys.exit()

try:
    # start the main function
    loop.run_until_complete(blink(board, DIGITAL_PIN))
    loop.run_until_complete(board.reset_board())
except KeyboardInterrupt:
    loop.run_until_complete(board.shutdown())
    sys.exit(0)

To exit your application cleanly, you should always call the shutdown method.

You may also wish to call the reset_board method when exiting to do a hardware reset of the Pico.

The init Method

For most applications, when instantiating the library, you can accept all the default parameters.

board = tmx_pico_aio.TmxPicoAio()

However, several parameters offered by the __init__ method allow for some additional control.


    def __init__(self, com_port=None, pico_instance_id=None,
                 sleep_tune=0.000001,
                 autostart=True,
                 loop=None,
                 shutdown_on_exception=True,
                 close_loop_on_shutdown=True,
                 reset_on_shutdown=True):

        """

        :param com_port: e.g. COM3 or /dev/ttyACM0.
                         Only use if you wish to bypass auto com port
                         detection.

        :param pico_instance_id: If not specified, than don't do id check.
                                 Else contains a board' s pico unique ID.
                                 This is passed as an array.

        :param sleep_tune: A tuning parameter (typically not changed by user)

        :param autostart: If you wish to call the start method within
                          your application, then set this to False.

        :param loop: optional user provided event loop

        :param shutdown_on_exception: call shutdown before raising
                                      a RunTimeError exception, or
                                      receiving a KeyboardInterrupt exception

        :param close_loop_on_shutdown: stop and close the event loop loop
                                       when a shutdown is called or a serial
                                       error occurs

        :para reset_on_shutdown: Reset the board upon shutdown

Let's take a look at these parameters.

com_port

If you have a single Pico connected to your computer, the library automatically finds and connects to the correct com port for your board. You may, however, override the auto-discovery routine and explicitly specify the port to use. This feature may be helpful if you wish to select the port manually.

pico_instance_id

Every Pico board has its own unique ID. This ID is displayed by the library whenever an application begins.

Retrieving pico ID...
Pico Unique ID: [230, 96, 68, 48, 67, 85, 0, 0]

You may use this parameter to ensure that a connection is made to the desired Pico board.

sleep_tune

This parameter is the sleep value expressed in seconds and is used at several strategic points in the client. For example, the serial receiver continuously checks the serial port receive buffer for an available character to process. If there is no character in the buffer, the client sleeps for the sleep_tune period before checking again.

Typically, you would accept the default value.

autostart

Typically, you wish to have your program start all tasks automatically, however, you may delay startup by setting this parameter to False and add your custom code before calling the start_aio method

loop

You may specify an asyncio loop to use. The default is to allow the system to use the default event loop.

shutdown_on_exception

When this parameter is set to True, the library shutdown method is automatically called when an exception is detected and all reporting is disabled.

By setting this parameter to False, the Pico may continue to send data to your application even after restarting it.

The default is True and is recommended to be used.

close_loop_on_shutdown

Typically the event loop is shutdown when the application exits. If you wish to leave event loop open, set this parameter False.

reset_on_shutdown

When set to True (the default), this parameter will send a message to the Pico to reset itself. After resetting, the Pico board LED will flash twice, indicating the Pico has been reset.