原理
读取/sys/class/thermal/thermal_zone0/temp文件，返回树莓派温度，控制GPIO产生PWM，从而实现温控风扇的控制。
C/C++代码
命令行操作
cd /home/pi/code/basic/fannano fan.c#复制代码gcc fan.c -o fan -lwiringPi./fan
#include <stdio.h>#include <stdlib.h> #include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include "wiringPi.h"//添加库文件#include "softPwm.h"//添加库文件#define TEMP_PATH "/sys/class/thermal/thermal_zone0/temp"#define MAX_SIZE 32#define PWM_Pin 25 //定义PWM_Pin引脚static int GetDuty(int temp);unsigned int Duty = 0;int main(void) {int fd;double temp = 0;char buf[MAX_SIZE];wiringPiSetup();//初始化wiringPisoftPwmCreate(PWM_Pin,0,100);//当前pwmRange为100，频率为100Hz，若pwmRange为50时，频率为200，若pwmRange为2时，频率为5000。softPwmWrite(PWM_Pin,50);//占空比 = value/pwmRange，当前占空比 = 50/100 = 50%while(1){// 打开/sys/class/thermal/thermal_zone0/tempfd = open(TEMP_PATH, O_RDONLY);if (fd < 0) {fprintf(stderr, "failed to open thermal_zone0/temp\n");return -1;}// 读取内容if (read(fd, buf, MAX_SIZE) < 0) {fprintf(stderr, "failed to read temp\n");return -1;}// 转换为浮点数打印temp = atoi(buf) / 1000.0;// 关闭文件close(fd);Duty = GetDuty(temp);softPwmWrite(PWM_Pin,Duty);printf("temp: %.2f,Duty: %d\n", temp, Duty);delay(1000*10);}}static int GetDuty(int temp){if(temp >= 60){return 100;}else if(temp >= 55){return 90;}else if(temp >= 53){return 80;}else if(temp >= 50){return 70;}else if(temp >= 45){return 60;}else{return 50;}}
python程序
import RPi.GPIO as GPIO #导入gpio口驱动模块import time #导入时间模块pwm_pin = 26 #定义pwm输出引脚(注意BCM编码的对应关系)GPIO.setmode(GPIO.BCM) #定义树莓派gpio引脚以BCM方式编号GPIO.setup(pwm_pin,GPIO.OUT) #使能gpio口为输出pwm = GPIO.PWM(pwm_pin,100) #定义pwm输出频率pwm.start(50) #占空比（范围：0.0 <= >= 100.0）while(1):# 打开文件file = open("/sys/class/thermal/thermal_zone0/temp")# 读取结果，并转换为浮点数temp = float(file.read()) / 1000# 关闭文件file.close()if(temp >= 60):Duty = 100elif(temp >= 55):Duty = 90elif(temp >= 53):Duty = 80elif(temp >= 50):Duty = 70 elif(temp >= 45):Duty = 60else:Duty = 50pwm.ChangeDutyCycle(Duty)# 向控制台打印print("temp : %.1f,duty : %d" %(temp,Duty))time.sleep(10)
开机自启动
制作sh脚本
#!/bin/bash/home/pi/code/basic/fan/fan
通过桌面自启动
mkdir .config/autostartnano .config/autostart/fan.desktop#内容[Desktop Entry]Type=ApplicationName=fanNoDisplay=trueExec=/home/pi/code/basic/fan/fan.shsudo reboot
参考：
[1]/xukai871105/article/details/38349209
[2]/weixin_42078116/article/details/119329536
[3]/build.html?id=4182&cid=308
[4]/build.html?id=2679&cid=308
[5]/qq_42714905/article/details/97131771
