CPU fan speed control settings for Raspberry Pi (fan_speed.py should be placed in /usr/bin, and fanctrl.service should be placed in /etc/systemd/system if the operating system is Raspbian); The dependency should be installed by pip install RPi.GPIO

fan_speed.py

#!/usr/bin/env python3
# -*- coding:utf-8 -*-
import logging
import RPi.GPIO
import time


logging.basicConfig(
    level=logging.INFO,
    format=(
        "[%(levelname)s]: %(message)s"
    ),
)

RPi.GPIO.setwarnings(False)
RPi.GPIO.setmode(RPi.GPIO.BCM)
RPi.GPIO.setup(2, RPi.GPIO.OUT)
pwm = RPi.GPIO.PWM(2, 100)
RPi.GPIO.setwarnings(False)

UPPER_THRESHOLD = 43 
LOWER_THRESHOLD = 33
try:
    while True:
        with open( '/sys/class/thermal/thermal_zone0/temp' ) as f:
            cpu_temp = int(f.read()) / 1000

        if cpu_temp >= LOWER_THRESHOLD:
            #启动时防止风扇卡死先全功率转0.1秒
            pwm.start(0)
            pwm.ChangeDutyCycle(100)
            time.sleep(.1)

            slope = (100 - 0) / (UPPER_THRESHOLD - LOWER_THRESHOLD)
            speed_level = min(int(slope * (cpu_temp - LOWER_THRESHOLD)), 100)
            pwm.ChangeDutyCycle(speed_level)

            logging.info("cpu temp:{:.2f}'C - fan on (speed level:{:d}%)".format(cpu_temp, speed_level))
        else:
            pwm.stop()
            logging.info("cpu temp:{:.2f}'C - fan off".format(cpu_temp))

        time.sleep(5)
except KeyboardInterrupt:
    pwm.stop()

fanctrl.service

[Unit]
Description=A fan speed controlling service
After=multi-user.target

[Service]
ExecStart=/usr/bin/fan_speed.py

[Install]
WantedBy=multi-user.target