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