209.58.142.155: Migrated comment #26

2018-10-26T11:02:00Z

Migrated comment #26

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#!/usr/bin/python
# MyRPi.ca script - ocs11@hotmail.com

# 2018-10-01

# Python script that uses multiple sources to determine the CPU and enclosure temperature
# and adjust the fan speed automatically

# Load system libraries
import RPi.GPIO as GPIO # Required to access the GPIO pin for PWM control.
import time # Required for the loop delay. [time.sleep]
import datetime # Required for date and time strings
import sys # Required for CTRL-C clean exit. [sys.exit]
import os # Required for secondary CPU temperature extraction. [os.open]
import smbus # Required to read the sensor temperature

# User Configuration Settings
FAN_PIN = 12 # BCM pin used to drive the fan control.
WAIT_TIME = 30 # Time, in seconds, to wait between each loop cycle.

fanSpeedMin = 36 # Minimum fan speed. Must be greater than 0. Use the calibration utility to get this value.
fanSpeedMax = 100 # Maximum fan speed. Set to limit noise otherwise leave at 100. Maximum 100.
cpuTempMin = 45 # Temperature at which to start the fan. Minimum 1.
cpuTempMax = 60 # Temperature at which fan should run at [fanSpeedMax] speed. Maximum 70 (for safety).

diagCon = 0 # Set to [1] to enable diagnostic output to the console. [0] to diable.
diagLog = 1 # Set to [1] to enable diagnostic output to a log file. [0] to diable.
fanStatusLog = "/tmp/fanStatus" # Diagnostic Log file path and filename.

# I2C Temperature LM75 sensor onboard Fan/power hat
# i2cdetect -y 1
# 0 1 2 3 4 5 6 7 8 9 a b c d e f
#00: -- -- -- -- -- -- -- -- -- -- -- -- --
#10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
#20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
#30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
#40: -- -- -- -- -- -- -- -- 48 -- -- -- -- -- -- -- <- 0x48 LM75 Temperature Sensor
#50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
#60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- <- 0x68 DS3231 RTC Module
#70: -- -- -- -- -- -- -- --
checkLM75 = 1 # Enable (1) or disable (0) the LM75 sensor check
sensorAddress = 0x48 # I2C Address of the temperature sensor
tempRegister = 0 # In progress
I2Cbus = smbus.SMBus(1) # 0 or 1 depending on the RPi. 0=/dev/i2c-0 1=/dev/i2c-1

# End of typical user configuration. Changing the code below may result in unexpected behaviour.

# Initialize runtime variables
PWM_FREQ = 50 # [Hz] Do not change. See documentation.
cpuTemp = 0 # CPU Temperatue
cpuTempOld = 0 # CPU Temperature on the last cycle
fanSpeed = 0 # Fan Speed
fanSpeedOld = 0 # Fan Speed on the last cycle
fanRunning = 1 # Boolean to store if the fan is running or not

def regdata2float (regdata):
return (regdata / 32.0) / 8.0

def getCPUtemp1():
if (diagCon): print "Trying to acquire CPU Temperature (Primary)."
if (diagLog): fileLog.write ( "Trying to acquire CPU Temperature (Primary).\n" )
cpuTempFile = open("/sys/class/thermal/thermal_zone0/temp","r") # Open system file Read-Only
cpuTemp1 = int(float(cpuTempFile.read())/1000) # Retrieve the system temperature value
cpuTempFile.close() # Close the system file
return cpuTemp1

def getCPUtemp2():
if (diagCon): print "Trying to acquire CPU Temperature (Secondary)."
if (diagLog): fileLog.write ( "Trying to acquire CPU Temperature (Secondary).\n" )
cpuTemp2 = os.popen('vcgencmd measure_temp').readline()
return float(cpuTemp2.replace("temp=","").replace("'C\n",""))

def getSensorTemp(self):
# Read the temperature from the I2C LM75 sensor
if (diagCon): print "Trying to acquire LM75 Sensor Temperature."
if (diagLog): fileLog.write ( "Trying to acquire LM75 Sensor Temperature.\n" )
raw = I2Cbus.read_word_data(sensorAddress, tempRegister) & 0xFFFF
raw = ((raw << 8) & 0xFF00) + (raw >> 8)
ret = regdata2float(raw)
if (diagCon): print "LM75 Sensor Temperature is ", ret, "C"
if (diagLog): fileLog.write ( "LM75 Sensor Temperature is " + str(ret) + " C\n" )
return ret

# Verify the configuration values
if ((cpuTempMin >= cpuTempMax) or (cpuTempMin < 1) or (cpuTempMax > 70)):
print "Invalid cpuTempMin or cpuTempMax value has been configured. Please read the documentation. Aborting."
exit(0)
if ((fanSpeedMin >= fanSpeedMax) or (fanSpeedMin < 0) or (fanSpeedMax > 100)):
print "Invalid fanSpeedMin or fanSpeedMax value has been configured. Please read the documentation. Aborting."
exit(0)

# Initialize the GPIO subsystem
GPIO.setmode(GPIO.BCM)
GPIO.setup(FAN_PIN, GPIO.OUT, initial=GPIO.LOW)
GPIO.setwarnings(False)
fan = GPIO.PWM(FAN_PIN,PWM_FREQ)
fan.start(0);

# Main runtime loop
try:
while (1): # Repeat until CTRL-C is pressed.

# Reset variables at beginning of loop
cpuTemp = 0
now = datetime.datetime.now()
timeNow = now.strftime("%Y-%m-%d %H:%M:%S")
if (diagCon): print timeNow
if (diagLog):
fileLog = open(fanStatusLog,"w")
fileLog.write ( timeNow + "\n" )

# Try method 1 to acquire CPU Temperature
cpuTemp = getCPUtemp1()

# If method 1 failed, try method 2 to get CPU temperature
if ((cpuTemp <= 0) or (cpuTemp > 120)):
cpuTemp = getCPUtemp2()

# Check to make sure we have a reasonable CPU temperature to work with
if ((cpuTemp <= 0) or (cpuTemp > 120)):
print "Unable to read the CPU Temperature [cpuTemp]. Incompatible system architecture or Linux version. Aborting."
exit(0)
if (diagCon): print "CPU Temperature: ", cpuTemp
if (diagLog): fileLog.write ( "CPU Temperature: " + repr(cpuTemp) + "\n" )

# Calculate the appropriate fan speed based on the current CPU temperature
if (cpuTemp > cpuTempMin):
cpuTempPerc = (((cpuTemp - cpuTempMin) * 100) / (cpuTempMax - cpuTempMin))
fanSpeed = (((fanSpeedMax - fanSpeedMin) * cpuTempPerc ) / 100 ) + fanSpeedMin
if (diagCon): print "Calculated cpuTempPerc:", cpuTempPerc, "% fanSpeed:", fanSpeed
if (diagLog): fileLog.write ( "Calculated cpuTempPerc: " + str(cpuTempPerc) + "% fanSpeed: " + str(fanSpeed) + "\n" )

# Enforce maximum fan speed
if ((fanSpeed > fanSpeedMax) or (cpuTemp >= cpuTempMax)):
if (diagCon): print "Setting fanSpeed [", fanSpeed, "] -> fanSpeedMax [", fanSpeedMax, "] based on fanSpeedMax or cpuTempMax"
if (diagLog): fileLog.write ( "Setting fanSpeed [" + str(fanSpeed) + "] -> fanSpeedMax [" + str(fanSpeedMax) + "] based on fanSpeedMax or cpuTempMax\n" )
fanSpeed = fanSpeedMax

# If fanSpeed is at or below the minimum, stop the fan
if (((fanSpeed < fanSpeedMin) or (cpuTemp <= cpuTempMin)) and (fanRunning != 0)):
if (diagCon): print "Changing Duty Cycle [", fanSpeedOld, "] -> [Off] Cooling not required."
if (diagLog): fileLog.write ( "Changing Duty Cycle [" + str(fanSpeedOld) + "] -> [Off] Cooling not required\n" )
fanSpeed = fanSpeedMin
fanSpeedOld = fanSpeedMin
fanRunning = 0
fan.ChangeDutyCycle(100)

# If the calculated speed is different from the last cycle, set the fan speed
if ((fanSpeed != fanSpeedOld)):
if (diagCon): print "Changing Duty Cycle [", fanSpeedOld, "] -> [", fanSpeed, "]"
if (diagLog): fileLog.write ( "Changing Duty Cycle [" + str(fanSpeedOld) + "] -> [" + str(fanSpeed) + "]\n" )
fanRunning = 1
fan.ChangeDutyCycle(100-fanSpeed)

fanSpeedOld = fanSpeed
if (checkLM75): getSensorTemp(I2Cbus)

# Wait until the next loop cycle
if (diagCon): print
if (diagLog): fileLog.close()
time.sleep(WAIT_TIME)

# If a keyboard interrupt occurs (ctrl + c), set the GPIO to 0 and exit the program.
except(KeyboardInterrupt):
print "Fan speed control script interrupted by the user. CTRL-C was pressed."
GPIO.cleanup()
if not fileLog.closed: fileLog.close()
sys.exit()

# End of Script

CommentStreams:98b4f6ee1f2db4c26065155d713b9f0e - Revision history

209.58.142.155: Migrated comment #26