Talk Sketch: Pointless Blinking: Evolution

gpiod Intro

blueprints/gpiod-demo.py

• gpiod basics, Box

  • Show center on/off

  • Quickly explain request_lines() (request.set_value() vs. request.set_values())

  • Show blink.glt2024.box

  • Use Box.matrix

  • insert snippets/blink, and use it

asyncio Intro

• threading

  • insert snippets/threads

  • strace -f ... ⟶ PIDs

  • Complain about threads

• Change to asyncio

• strace -f ... again ⟶ no PIDs

And blink?

blueprints/blink-demo.py

• Explain on ⟶ asyncio.create_future()

• sleep

• Combine through any ⟶ launch_isolated

• forever and sequence ⟶ blink

forever(
    sequence(
        any(
            on(box.matrix.get(2,2)),
            sleep(0.5),
        ),
        sleep(0.5),
    )
)

• Pull in snippet blueprints/snippet-nice-pattern

gpiod, And Interrupts

blueprints/gpiod-interrupts.py

• blink.base.sleep: timer event

• Other events? ⟶ interrupt on GPIO line

• Show blueprints/gpiod-interrupts.py

• Discuss edges, timestamps, bouncing

• FALLING, debounce_period

• Transform into generator, events()

Nice, Pythonic!

gpiod, Interrupts, and asyncio

blueprints/gpiod-interrupts.py

• async def main(); simply iterate over events()

• ⟶ works

• Second button, 19? Hm, tasks.

• Wrap events() iteration in print_events()

• Make print_events() async

• In main(), create two tasks around print_events()

• ⟶ one works, the other not

We block! Aha, async all over

• Question: how make events() async? asynchronous generator?

• Future, loops, blah

And blink?

• Show wait_button

• back in blink-demo.py, replace sleep(3) with wait_button()

textual

• Show https://pypi.org/project/textual-imageview/

Python 3.12 Installation (for TaskGroup)

$ sudo apt install libssl-dev libreadline-dev libffi-dev libsystemd-dev python3-dev
$ wget https://www.python.org/ftp/python/3.12.2/Python-3.12.2.tar.xz
$ tar xf Python-3.12.2.tar.xz
$ cd Python-3.12.2/
$ ./configure --prefix=$HOME/Python-3.12.2-Install --with-readline
$ make
$ make install