Add pwm fan contorl code

fan_contorl.py

@@ -0,0 +1,67 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+import RPi.GPIO as GPIO
+import time
+import signal
+import sys
+import os
+
+# Configuration
+FAN_PIN = 18            # BCM pin used to drive PWM fan
+WAIT_TIME = 3           # [s] Time to wait between each refresh
+PWM_FREQ = 25000        # [Hz] 25kHz for Noctua PWM control
+
+# Configurable temperature and fan speed
+MIN_TEMP = 40
+MAX_TEMP = 65
+FAN_LOW = 40
+FAN_HIGH = 90
+FAN_OFF = 0
+FAN_MAX = 100
+
+# Get CPU's temperature
+def getCpuTemperature():
+    res = os.popen('vcgencmd measure_temp').readline()
+    temp =(res.replace("temp=","").replace("'C\n",""))
+    #print("temp is {0}".format(temp)) # Uncomment for testing
+    return temp
+
+# Set fan speed
+def setFanSpeed(speed):
+    fan.start(speed)
+    return()
+
+# Handle fan speed
+def handleFanSpeed():
+    temp = float(getCpuTemperature())
+    # Turn off the fan if temperature is below MIN_TEMP
+    if temp < MIN_TEMP:
+        setFanSpeed(FAN_OFF)
+        #print("Fan OFF") # Uncomment for testing
+    # Set fan speed to MAXIMUM if the temperature is above MAX_TEMP
+    elif temp > MAX_TEMP:
+        setFanSpeed(FAN_MAX)
+        #print("Fan MAX") # Uncomment for testing
+    # Caculate dynamic fan speed
+    else:
+        step = (FAN_HIGH - FAN_LOW)/(MAX_TEMP - MIN_TEMP)   
+        temp -= MIN_TEMP
+        setFanSpeed(FAN_LOW + ( round(temp) * step ))
+        #print(FAN_LOW + ( round(temp) * step )) # Uncomment for testing
+    return ()
+
+try:
+    # Setup GPIO pin
+    GPIO.setwarnings(False)
+    GPIO.setmode(GPIO.BCM)
+    GPIO.setup(FAN_PIN, GPIO.OUT, initial=GPIO.LOW)
+    fan = GPIO.PWM(FAN_PIN,PWM_FREQ)
+    setFanSpeed(FAN_OFF)
+    # Handle fan speed every WAIT_TIME sec
+    while True:
+        handleFanSpeed()
+        time.sleep(WAIT_TIME)
+
+except KeyboardInterrupt: # trap a CTRL+C keyboard interrupt
+    setFanSpeed(FAN_HIGH)
+    #GPIO.cleanup() # resets all GPIO ports used by this function