由于没有支持pwm的风扇，所以没有实测：

引脚和接线图：

参考文献

https://blog.csdn.net/luzze__123/article/details/118641526

S8050三极管基极(b)串联1K电阻（可省略）接树莓派GPIO12号引脚（硬件pwm引脚）

风扇正极接树莓派GPIO4号引脚(5V)

风扇负极接三极管集电极（c）

三极管发射极（e）接GPIO6号引脚（地GND）

Python版：

pwm案例1：

# -*- coding: utf-8 -*-
 
import RPi.GPIO as GPIO
import time
 
# 控制风扇的GPIO
FAN_GPIO = 11
# 低温阈值，低于它则关闭风扇
MIN_TEMP = 35
# 高温阈值，高于它则全速运转
MAX_TEMP = 55
# 多长时间读取一次CPU温度，单位秒
SAMPLING = 30
 
 
# 单位为千分之一度
def get_cpu_temp():
    with open('/sys/class/thermal/thermal_zone0/temp') as f:
        cpu_temp = int(f.read())
    return cpu_temp
 
 
def main():
    GPIO.setwarnings(False)
    GPIO.setmode(GPIO.BOARD)
    GPIO.setup(FAN_GPIO, GPIO.OUT)
 
    # 初始化PWM的频率，frequency=50Hz
    pwm = GPIO.PWM(FAN_GPIO, 50)
    # 为防止风扇卡死，开机全速运行n秒
    pwm.start(100)
    time.sleep(5)
    pwm.stop()
 
    try:
        while 1:
            temp = get_cpu_temp()
            print('CPU temperature:', temp)
            if temp < MIN_TEMP * 1000:
                # 低于低温阈值，则关闭风扇
                print('fan to stop running')
                pwm.stop()
            elif temp > MAX_TEMP * 1000:
                # 超过高温阈值，则全速运行
                print('full-speed operation')
                pwm.start(100)
            else:
                # 在低温阈值和高温阈值之间时，则根据占空比使用PWM控制风扇转速。
                dc = (temp - MIN_TEMP * 1000) * 100 / ((MAX_TEMP - MIN_TEMP) * 1000)
                pwm.start(dc)
                print('PWM duty cycle:', dc)
            # 设置采样频率
            time.sleep(SAMPLING)
    except KeyboardInterrupt:
        pass
 
    pwm.stop()
    GPIO.cleanup()
 
 
if __name__ == '__main__':
    main()

pwm案例2

import RPi.GPIO as gpio
import time
fan_gpio_pin = 12
temp_max = 500
temp_on = 450
temp_min = 400
def get_cpu_temp():
    with open('/sys/class/thermal/thermal_zone0/temp') as f:
        cpu_temp = int(f.read())
    return cpu_temp/100

def main():
    gpio.setwarnings(False)
    gpio.setmode(gpio.BOARD)
    gpio.setup(fan_gpio_pin, gpio.OUT, initial=gpio.LOW)
    pwm = gpio.PWM(fan_gpio_pin, 50)
    hasFanStarted = False
    while True:
        temp = get_cpu_temp()
        # print(temp)
        if temp < temp_min:
            if hasFanStarted:
                pwm.start(0)
                hasFanStarted = False
        elif temp >= temp_on and temp <= temp_max:
            pwm.start(temp-temp_on+50)
            hasFanStarted = True

        elif temp > temp_max:
            pwm.start(100)
            hasFanStarted = True
        time.sleep(1)

if __name__ == '__main__':
    main() 

开关控制：

import RPi.GPIO as gpio
from time import sleep

Temper_HI = 47  # 风扇启动温度
Temper_LO = 40  # 风扇关闭温度
gpio_pin = 12
# 初始化GPIO针脚控制
gpio.setmode(gpio.BOARD)
gpio.setup(gpio_pin, gpio.OUT)

while True:
    with open("/sys/class/thermal/thermal_zone0/temp", "r") as f:
        temper = int(f.read()) // 100 / 10  # 计算温度，保留一位小数
    # print(temper)
    if temper > Temper_HI:
        gpio.output(gpio_pin, gpio.HIGH)

    if temper < Temper_LO:
        gpio.output(gpio_pin, gpio.LOW)
    sleep(1) 

shell控制

案例1：

#! /bin/bash
fan_is_on=0
if [ ! -e "/sys/class/gpio/gpio18/value" ]
    then
    echo "export gpio 18"
    echo "18" > "/sys/class/gpio/export"
fi

echo "out" > "/sys/class/gpio/gpio18/direction"

while ((1))
do
TEMP=$(cat /sys/class/thermal/thermal_zone0/temp)
echo $TEMP
if [[ $fan_is_on -eq 1 ]] && [[ $TEMP -lt 40000 ]]
    then
    fan_is_on=0
    echo "fan off"
    echo "0" > "/sys/class/gpio/gpio18/value"
elif [[ $fan_is_on -eq 0 ]] && [[ $TEMP -gt 45000 ]]
    then
    fan_is_on=1
    echo "fan on"
    echo "1" > "/sys/class/gpio/gpio18/value"
fi
sleep 1s
done 

案例2

#!/bin/bash
 echo 14 > /sys/class/gpio/export
 echo out > /sys/class/gpio/gpio14/direction
 echo 1 > /sys/class/gpio/gpio14/value
 sleep 2
 while true
 do
     cputemp=`cat /sys/class/thermal/thermal_zone0/temp`
     valve=70000
     temp=`expr $cputemp`
     echo $temp
     if (( $temp >= $valve ))
     then
         echo 1 > /sys/class/gpio/gpio14/value &
     else
         echo 0 > /sys/class/gpio/gpio14/value &
     fi
     sleep 60
 done