42 lines
982 B
Python
42 lines
982 B
Python
#!/usr/bin/python
|
|
# -*- coding: utf-8 -*-
|
|
import RPi.GPIO as GPIO
|
|
import time
|
|
|
|
# Pin configuration
|
|
TACH = 24 # Fan's tachometer output pin
|
|
PULSE = 2 # Noctua fans puts out two pluses per revolution
|
|
WAIT_TIME = 1 # [s] Time to wait between each refresh
|
|
|
|
# Setup GPIO
|
|
GPIO.setmode(GPIO.BCM)
|
|
GPIO.setwarnings(False)
|
|
GPIO.setup(TACH, GPIO.IN, pull_up_down=GPIO.PUD_UP) # Pull up to 3.3V
|
|
|
|
# Setup variables
|
|
t = time.time()
|
|
rpm = 0
|
|
|
|
# Caculate pulse frequency and RPM
|
|
def fell(n):
|
|
global t
|
|
global rpm
|
|
|
|
dt = time.time() - t
|
|
if dt < 0.005: return # Reject spuriously short pulses
|
|
|
|
freq = 1 / dt
|
|
rpm = (freq / PULSE) * 60
|
|
t = time.time()
|
|
|
|
# Add event to detect
|
|
GPIO.add_event_detect(TACH, GPIO.FALLING, fell)
|
|
|
|
try:
|
|
while True:
|
|
print "%.f RPM" % rpm
|
|
rpm = 0
|
|
time.sleep(1) # Detect every second
|
|
|
|
except KeyboardInterrupt: # trap a CTRL+C keyboard interrupt
|
|
GPIO.cleanup() # resets all GPIO ports used by this function |