Pin Interrupt not working as expected

[jackalope]

My Apologies if this is answered elsewhere. But I'm running into an odd issue that with my Lopy4 and expansion board. I'm setting up a pin with a callback and regardless of what trigger I use it immediately fires off and not again afterwards. Running the following code will immediately kick off the testing() function, if I press the back_button I can confirm its value goes from 1 to 0 but doesn't fire the callback. I've tried low_level, high_level, rising and falling values for the trigger. All behave the same.

from machine import I2C, Pin
import time


def testing():
    print("test function")


back_button = Pin('P8', Pin.IN, Pin.PULL_UP)

back_button.callback(Pin.IRQ_FALLING, testing())

For cabling I have a simple button going to P8 on one side and ground on the other.

Calling the callback from the repl returns the following which I'm not sure is expected behavior or not.

>>> back_button.callback(Pin.IRQ_FALLING, testing())
test function

Lopy version info:
Pycom MicroPython 1.20.2.r1 [v1.11-a5aa0b8] on 2020-09-09; LoPy4 with ESP32
Pybytes Version: 1.6.0

Thank you in advance!

[jackalope]

@jcaron, I'm such a fool. I had a feeling it had to be something stupid simple. Thank you!

[jcaron]

@jackalope remove the (). You want to pass the function, not the result of calling that function.