Problem with interrupts on Raspberry Pi Pico - newbee with problems

[dhopet]

I'm building a three digit 7-segment LED counter by the use of a Pico and 74HC595 shift registers.
This is my goal:
When a positive (3,3V) pulse comes in on GPIO 14, the counter has to be added by 1.
When a positive(3,3V) pulse comes in on GPIO 15, 1 has to be subtracted from the counter.
Quite simple, isn't it?
But..., it doesn't work!
The IRQ fires before any pulse comes in! How is that even possible? What am I doing wrong?
Who will be so kind to wach my code?

from machine import Pin
import utime
import random

#GPIO's for 74HC595 shift-registers
dataPIN=Pin(2, Pin.OUT)
latchPIN=Pin(4, Pin.OUT)
clockPIN=Pin(3, Pin.OUT)

#GPIO's for count pulses (up and down)
upPIN = Pin(14, Pin.IN, Pin.PULL_DOWN)
downPIN = Pin(15, Pin.IN, Pin.PULL_DOWN)

Counter = 0

#7-segment digits (00000000 is for leading zero's)
bit_string = [
"00111111",
"00000110",
"01011011",
"01001111",
"01100110",
"01101101",
"01111101",
"00000111",
"01111111",
"01101111",
"00000000"
]

#shifting in data in three 74HC595's
def shift_update(input,data,clock,latch):
  #make latch low
  latch.value(0)
  
  #shifting in data
  for i in range(0 , 24):
    clock.value(0)
    data.value(int(input[i]))
    clock.value(1)
    clock.value(0)

  #make latch high to show displays
  latch.value(1)

#when starting the program, all three displays are cleared.
shift_update(bit_string[10] + bit_string[10] + bit_string[10], dataPIN, clockPIN, latchPIN)

#handler for adding counter
def add():
    global Counter
    Counter +=1
    counting (Counter)

#handler for substracting counter
def subtract():
    global Counter
    Counter -=1
    counting (Counter)

#splitting counter in units, tens and hundreds
def counting (Counter):
    if Counter < 10 :
        Units = Counter
        shift_update(bit_string[Units] + bit_string[10] + bit_string[10], dataPIN, clockPIN, latchPIN)
    elif Counter > 9 and Counter < 100:
        Units = Counter % 10
        Tens = Counter // 10
        shift_update(bit_string[Units] + bit_string[Tens] + bit_string[10], dataPIN, clockPIN, latchPIN)
    elif Counter > 99 and Counter < 1000 :
        Units = Counter % 10
        Tens = (Counter // 10) % 10
        Hundreds = Counter // 100
        shift_update(bit_string[Units] + bit_string[Tens] + bit_string[Hundreds], dataPIN, clockPIN, latchPIN)

#IRQ routines
upPIN.irq(trigger = upPIN.IRQ_RISING, handler = add())
downPIN.irq(trigger = downPIN.IRQ_RISING, handler = subtract())

while True:
    if Counter < 0:
        Counter = 0
    elif Counter > 999:
        Counter = 999
    

`

[GitHubsSilverBullet]

Please do us a favor and reformat your sourcecode appropriately.
Three backticks followed by the word python and newline.
Then the sourcecode.
Thanks

[GitHubsSilverBullet]

Those two lines:

upPIN.irq(trigger = upPIN.IRQ_RISING, handler = add())
downPIN.irq(trigger = downPIN.IRQ_RISING, handler = subtract())

need a change:

upPIN.irq(trigger = upPIN.IRQ_RISING, handler = add)
downPIN.irq(trigger = downPIN.IRQ_RISING, handler = subtract)

[dhopet]

Thank you so much GitHubsSilverBullet, it does the job now! So simple, could have searched ages for that!

[peterhinch]

The reason is as follows.

handler = add

assigns the add function to handler, whereas

handler = add()

runs the add() function. In Python the return value of a function with no return statement is None. The line of code therefore assigns None to handler.

[dhopet]

Thank you, peterhinch, it's clear to me now!