rising edge of detection

[peter14]

Hello,
thank you, it works. I do a code to print the speed of the encoder bu it does'nt works, the max that he prints is 4, i think it's a probleme like the speed of python to detect rising edge. Can you help me because i need the speed but i dont know how to do now. My first idea is mesuring the time between two riing edge and after calculate the speed but it doesn't works. Do you have other idea of code that could works?

# coding: utf-_
import RPi.GPIO as GPIO
import time

lasttime=0
 
def callback_up(channel):
    global lasttime
    if lasttime==0:
        lasttime=time.time()
    else:
        now = time.time()
        gap=now-lasttime
        vitesse=(1/(gap*256))*257
        print(vitesse)
        lasttime=now
    
 
GPIO.setmode(GPIO.BCM)
PIR = 23
GPIO.setup(PIR, GPIO.IN)
try:
    GPIO.add_event_detect(PIR, GPIO.RISING, callback=callback_up)
    while 1:
        time.sleep(10)
exept KeyboardInterrupt:
   print("fin")