gpiozero combining button events in event driven code

Question

I'm pretty new to the Python and Raspberry business and am currently working on my first major application. I like gpiozero and the ability to work with events throughout.

I would like to make my code "event-driven" and "actually" (maybe) only have a beauty question. I would like to query different states in combination. Examples:

BTN1 + BTN2 => Event 1

BTN1 + !BTN2 => Event 2

BTN3 + BTN1 => Event 3 etc.

Is there a nice way to combine the signals here?

I have seen that you could do something like this: led.source = all_values(btn1, btn2) However, this is not enough for me; I have to call up my own functions in any case.

My only current idea would be something like this:

button1 = Button(1)
button2 = Button(2)

def check_btns():
    if button1.is_pressed && button2.is_pressed:
       btn1_btn2_pressed()

def btn1_btn2_pressed():
    print("Both pressed")   

button1.when_pressed = check_btns
button2.when_pressed = check_btns

Does anyone know a more elegant solution for querying the events in combination?

Greetings

So you want to call one of 8 different function based on the state of the 3 buttons? — 001
– 001, Commented Sep 19, 2024 at 17:05
Fortunately, I don't need every combination, I was more interested in clarifying the problem. Specifically, I have 2x 2 inputs which are only queried in 2 combinations. There may be something else, but I can't estimate that yet. Ultimately, I'm just looking for a more elegant way :) — MaxWeb
– MaxWeb, Commented Sep 19, 2024 at 17:41

001 · Accepted Answer · 2024-09-19 18:35:01Z

1

Not sure I understand the issue, but here's this...

You can use a bitmask where each bit represents the state of each button. For example:

0b1010
  |||^- button 1 state
  ||^-- button 2 state
  |^--- button 3 state
  ^---- button 4 state

Then you can use these values as keys in a dictionary where the values are functions:

def four_and_one():
    print("Buttons 1 and 4 pressed")

def two():
    print("Button 2 pressed")

funcs = {
    0b1001: four_and_one
    0b0010: two
    ...
}

Then, build the mask when you check the buttons:

def check_btns():
    mask = button1.is_pressed      | \
           button2.is_pressed << 1 | \
           button3.is_pressed << 2 | \
           button4.is_pressed << 3
    if mask in funcs:
         funcs[mask]()

answered Sep 19, 2024 at 18:35

001

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1 Comment

MaxWeb Over a year ago

Okay, that's a more elegant solution :) Not exactly what I was hoping for, but a good approach, thanks for that! I had hoped for a possibility directly from the gpiozero lib, but that probably remains just a wish^^

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