[Pi 4B] [LE12.0.1] Autostart.sh with python script for fan control won't work

Nathan.OTN · September 22, 2024 at 11:04 AM New

Hey everyone ! Hope you are well !

I am trying to have a fan control script working at startup. I have a Pi 4 with Libreelec 12.0.1 freshly installed with RPi tools addon. Fan is controlled by PWM on PIN 18.

The control script runs well when I use the command: python /storage/fan_control.py

Python

#! /usr/bin/env python3
import time
import signal
import sys
sys.path.append('/storage/.kodi/addons/virtual.rpi-tools/lib')
from gpiozero import PWMOutputDevice
import os

# Configuration
FAN_PIN = 18            # BCM pin used to drive PWM fan
WAIT_TIME = 2           # [s] Time to wait between each refresh
PWM_FREQ = 25           # [kHz] 25kHz for Noctua PWM control

# Configurable temperature and fan speed
MIN_TEMP = 42           # under this temp value fan is switched to the FAN_OFF speed
MAX_TEMP = 68           # over this temp value fan is switched to the FAN_MAX speed
FAN_LOW = 30            # lower side of the fan speed range during cooling
FAN_HIGH = 99           # higher side of the fan speed range during cooling
FAN_OFF = 20            # fan speed to set if the detected temp is below MIN_TEMP
FAN_MAX = 100           # fan speed to set if the detected temp is above MAX_TEMP

# Get CPU's temperature
def getCpuTemperature():
        with open('/sys/class/thermal/thermal_zone0/temp') as f:
                return float(f.read()) / 1000

def setFanSpeed(speed):
                pwm_fan.value = speed/100  # divide by 100 to get values from 0 to 1
                return()

# Handle fan speed
def handleFanSpeed():
        temp = float(getCpuTemperature())
        #print("cpu temp: {}".format(temp))
        # 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:
                pwm_fan = PWMOutputDevice(FAN_PIN, initial_value=0,frequency=PWM_FREQ) # initialize FAN_PIN as a pwm out>
                setFanSpeed(FAN_OFF) # initially set fan speed to the FAN_OFF value
                while True:
                                handleFanSpeed() # call the function that calculates the target fan speed
                                time.sleep(WAIT_TIME) # wait for WAIT_TIME seconds before recalculate

except KeyboardInterrupt: # trap a CTRL+C keyboard interrupt
                setFanSpeed(FAN_HIGH)

#finally:
#    pwm_fan.close() # in case of unexpected exit, resets pin status (fan will go full speed after exiting)

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I have created an autostart.sh file and it also works (fan is controlled) when I execute sh /storage/.config/autostart.sh

When I boot the Raspberry, the fan is always running at full speed which means the python script isn't launched.

Here is the result of systemctl status kodi-autostart.service:

Code

● kodi-autostart.service - Kodi user autostart script
● kodi-autostart.service - Kodi user autostart script
     Loaded: loaded (/usr/lib/systemd/system/kodi-autostart.service; disabled; p
     Active: active (exited) since Tue 2024-02-27 17:26:17 UTC; 6 months 25 days
    Process: 865 ExecStart=/bin/sh -c . /etc/profile; test -f /storage/.config/a
   Main PID: 865 (code=exited, status=0/SUCCESS)
      Tasks: 0 (limit: 1590)
        CPU: 572ms
     CGroup: /system.slice/kodi-autostart.service

Sep 22 09:56:43 KodiPi sh[899]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Sep 22 09:56:43 KodiPi sh[899]:   File "/storage/.kodi/addons/virtual.rpi-tools/
Sep 22 09:56:43 KodiPi sh[899]:     self.pin.frequency = frequency
Sep 22 09:56:43 KodiPi sh[899]:     ^^^^^^^^^^^^^^^^^^
Sep 22 09:56:43 KodiPi sh[899]:   File "/storage/.kodi/addons/virtual.rpi-tools/
Sep 22 09:56:43 KodiPi sh[899]:     lambda self, value: self._set_frequency(valu
Sep 22 09:56:43 KodiPi sh[899]:                         ^^^^^^^^^^^^^^^^^^^^^^^^
Sep 22 09:56:43 KodiPi sh[899]:   File "/storage/.kodi/addons/virtual.rpi-tools/
Sep 22 09:56:43 KodiPi sh[899]:     raise PinPWMUnsupported(  # pragma: no cover
Sep 22 09:56:43 KodiPi sh[899]: gpiozero.exc.PinPWMUnsupported: PWM is not suppo

~
~
~
standard input lines 1-19/19 (END)
KodiPi:~ # clear
● kodi-autostart.service - Kodi user autostart script
● kodi-autostart.service - Kodi user autostart script
     Loaded: loaded (/usr/lib/systemd/system/kodi-autostart.service; disabled; preset: disabled)
     Active: active (exited) since Tue 2024-02-27 17:26:17 UTC; 6 months 25 days ago
    Process: 865 ExecStart=/bin/sh -c . /etc/profile; test -f /storage/.config/autostart.sh && exec /bin/sh /storage/.config/autostart
   Main PID: 865 (code=exited, status=0/SUCCESS)
      Tasks: 0 (limit: 1590)
        CPU: 572ms
     CGroup: /system.slice/kodi-autostart.service

Sep 22 09:56:43 KodiPi sh[899]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Sep 22 09:56:43 KodiPi sh[899]:   File "/storage/.kodi/addons/virtual.rpi-tools/lib/gpiozero/output_devices.py", line 396, in __init__
Sep 22 09:56:43 KodiPi sh[899]:     self.pin.frequency = frequency
Sep 22 09:56:43 KodiPi sh[899]:     ^^^^^^^^^^^^^^^^^^
Sep 22 09:56:43 KodiPi sh[899]:   File "/storage/.kodi/addons/virtual.rpi-tools/lib/gpiozero/pins/__init__.py", line 379, in <lambda>
Sep 22 09:56:43 KodiPi sh[899]:     lambda self, value: self._set_frequency(value),
Sep 22 09:56:43 KodiPi sh[899]:                         ^^^^^^^^^^^^^^^^^^^^^^^^^^
Sep 22 09:56:43 KodiPi sh[899]:   File "/storage/.kodi/addons/virtual.rpi-tools/lib/gpiozero/pins/__init__.py", line 374, in _set_freq
Sep 22 09:56:43 KodiPi sh[899]:     raise PinPWMUnsupported(  # pragma: no cover
Sep 22 09:56:43 KodiPi sh[899]: gpiozero.exc.PinPWMUnsupported: PWM is not supported on pin GPIO18

~
~
~
~
KodiPi:~ #

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I have tried to increase the sleep delay in autostart.sh to 60 and 120 but it does not make any difference.

Any idea ?

HarryH · September 22, 2024 at 6:46 PM New

Please try this: Move the import line for os module upwards before you import from gpiozero and insert that line.

Python

import os
os.environ['LG_WD'] = '/tmp'
from gpiozero import PWMOutputDevice

LibreELEC 12 has been hardened. The lgpio module (used by gpiozero) needs a working directory path which isn't write protected: https://github.com/gpiozero/gpiozero/issues/1106

Nathan.OTN · September 22, 2024 at 8:25 PM New

It works !!!! Thank you so much HarryH

For those who wants details, here is the content of fan_control.py:

Python

#! /usr/bin/env python3
import os
import time
import signal
import sys
sys.path.append('/storage/.kodi/addons/virtual.rpi-tools/lib')
os.environ['LG_WD'] = '/tmp'
from gpiozero import PWMOutputDevice


# Configuration
FAN_PIN = 18            # BCM pin used to drive PWM fan
WAIT_TIME = 2           # [s] Time to wait between each refresh
PWM_FREQ = 25           # [kHz] 25kHz for Noctua PWM control

# Configurable temperature and fan speed
MIN_TEMP = 42           # under this temp value fan is switched to the FAN_OFF speed
MAX_TEMP = 68           # over this temp value fan is switched to the FAN_MAX speed
FAN_LOW = 30            # lower side of the fan speed range during cooling
FAN_HIGH = 99           # higher side of the fan speed range during cooling
FAN_OFF = 20            # fan speed to set if the detected temp is below MIN_TEMP
FAN_MAX = 100           # fan speed to set if the detected temp is above MAX_TEMP

# Get CPU's temperature
def getCpuTemperature():
        with open('/sys/class/thermal/thermal_zone0/temp') as f:
                return float(f.read()) / 1000

def setFanSpeed(speed):
                pwm_fan.value = speed/100  # divide by 100 to get values from 0 to 1
                return()

# Handle fan speed
def handleFanSpeed():
        temp = float(getCpuTemperature())
        #print("cpu temp: {}".format(temp))
        # 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:
                pwm_fan = PWMOutputDevice(FAN_PIN, initial_value=0,frequency=PWM_FREQ) # initialize FAN_PIN as a pwm output
                setFanSpeed(FAN_OFF) # initially set fan speed to the FAN_OFF value
                while True:
                                handleFanSpeed() # call the function that calculates the target fan speed
                                time.sleep(WAIT_TIME) # wait for WAIT_TIME seconds before recalculate

except KeyboardInterrupt: # trap a CTRL+C keyboard interrupt
                setFanSpeed(FAN_HIGH)

#finally:
#    pwm_fan.close() # in case of unexpected exit, resets pin status (fan will go full speed after exiting)

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Here is the content of autostart.sh:

Bash

#!/bin/bash
(
sleep 180
sh /storage/.config/fan_control.sh start
)&

Here is the content of fan_control.sh:

Code

#! /bin/sh

### BEGIN INIT INFO
# Provides:          fancontrol.py
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
### END INIT INFO

# Carry out specific functions when asked to by the system
case "$1" in
  start)
    echo "Starting fancontrol.py"
    /storage/fan_control.py &
    ;;
  stop)
    echo "Stopping fancontrol.py"
    pkill -f /storage/fan_control.py
    ;;
  *)
    echo "Usage: /storage/.config/fan_control.sh {start|stop}"
    exit 1
    ;;
esac

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