Talk Script: Python, asyncio, libgpiod, and Pointless Blinking¶

`gpiod` Intro ¶

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`?¶

Explain on(), sleep(), any(), forever()
Pull in snippet blueprints/snippet-nice-pattern
Ah, wait_button()
Revert to original blinking
Enclose in any(), limiting it to 3 secons

`gpiod`, And Interrupts ¶

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`¶

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`¶

My own stuff
```
$ ./run-menu.py
```
Show https://pypi.org/project/textual-imageview/
```
$ vimg ~/IMG<TAB>
```

`python-sdbus`¶

Start the server:

$ ./dbus-blink-server.py

On another terminal, use busctl

$ busctl --user list
$ busctl --user introspect <TAB>
$ busctl --user call ...