设计思路：

这个是一个STM32通过定时器产生PWM波控制小风扇的设计，首先STM32驱动ds18b20温度传感器采集环境温度，然后通过按键设置温度的阈值，不同的温度范围定时器产生的PWM波不同，相应的小风扇的转速也会不一样，温度越高，小风扇的转速越大。LCD1602显示屏显示当前温度，和设置的阈值，同时按键支持连按，也支持掉电数据保存。希望能够帮助到需要的朋友。需要参考的朋友可以在文章底部点击下载源码和原理图。

下面是main.c文件的代码

#include "stm32f10x.h"
#include "lcd.h"
#include <stdio.h>
#include "led.h"
#include "deputy.h"
#include "sys.h"
#include "delay.h"
#include "stmflash.h"
#include "ds18b20.h"
#include "LCD1602.h"void KEY_Scan(void);
u8   KEY_scan(u8 mode);
void display_tem(void);
unsigned char Uart1_Buff[1024];   //串口1缓冲数组
unsigned char Uart1_Count=0;      //串口1累加变量
u8 right=0,Tim_ms=0,state=0,s0=0,sec1=0,sec2=0,memory_flag=0;
float result=0.0000;
float table = 0.70;
int pm25Value;
float High,Low;u8 Tem_L[20]={0};
u8 Tem_H[20]={0};
u8 showBuffer[20] = {0};
uint8_t key1_flag=0,key2_flag=0,key3_flag=0;int main(void)
{delay_init();	GPIO_init();LCD1602_Init();TIM2_Int_Init(350,7199);	//10Khz,计数到5000是500msds18b20_init_x();GPIO_ResetBits(GPIOB,GPIO_Pin_10);GPIO_SetBits(GPIOB,GPIO_Pin_11);LCD1602_ClearScreen();
//	Test_Write(0x08009100,(float)30.1);
//	Test_Write(0x08009104,(float)19.2);High=STMFLASH_ReadHalfWord(0x08009100)/16.;Low=STMFLASH_ReadHalfWord(0x08009104)/16.;		while(1){	display_tem();if(memory_flag){memory_flag=0;Test_Write(0x08009100,High*16.);//float类型扩大十倍，方便存储数据Test_Write(0x08009104,Low*16.);}}	
}void display_tem(void)
{float tem;u16 z = 0;z	= ds18b20_read(); 	tem = z/16. ;LCD1602_Show_Str(0, 0, (unsigned char *)showBuffer);snprintf((char *)showBuffer, sizeof(showBuffer), "Cur_Tem:  %2.1f", tem);LCD1602_Write_Dat(0xDF);LCD1602_Write_Dat(0x43);snprintf((char *)Tem_H, sizeof(Tem_H), "H:%2.1f   L:%2.1f", High,Low);LCD1602_Show_Str(0, 1, (unsigned char *)Tem_H);	LCD1602_Write_Dat(0xDF);LCD1602_Write_Dat(0x43);if(tem>High){TIM3_PWM_Config(9999);}else if(tem>=Low&&tem<High){TIM3_PWM_Config(4000);}else if(tem<Low){TIM3_PWM_Config(2600);}	
}void KEY_Scan(void)
{if(KEY1==0){			state=(state+1)%3;}while(!KEY1);	if(KEY2==0){if(key2_flag==1){key2_flag=0;if(state==1){if((High>0)&&(High>=Low)) High+=0.1;elseHigh=Low+0.1;}else if(state==2){if((Low>0)&&(Low<=High))Low+=0.1;else Low=High-0.1;}}if(sec1==0){if(state==1){if((High>0)&&(High>=Low)) High+=0.1;elseHigh=Low+0.1;}else if(state==2){if((Low>0)&&(Low<=High))Low+=0.1;else Low=High-0.1;}}}else{sec1=7;if(key2_flag==0){key2_flag=1;memory_flag=1;			}			}if(KEY3==0){if(key3_flag==1){key3_flag=0;if(state==1){if((High>0)&&(High>=Low)) High-=0.1;elseHigh=Low+0.1;}else if(state==2){if((Low>0)&&(Low<=High))Low-=0.1;else Low=High-0.1;}		}if(sec2==0){if(state==1){if((High>0)&&(High>=Low)) High-=0.1;elseHigh=Low+0.1;}else if(state==2){if((Low>0)&&(Low<=High))Low-=0.1;else Low=High-0.1;}}}else{sec2=7;if(key3_flag==0){key3_flag=1;memory_flag=1;			}				}
}void TIM2_IRQHandler(void)   //TIM2中断
{if(TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)  //检查TIM2更新中断发生与否{TIM_ClearITPendingBit(TIM2, TIM_IT_Update);  //清除TIM2更新中断标志	Tim_ms++;if(Tim_ms%6==0){if(s0==1) s0=0;else s0=1;}KEY_Scan();if(state==1&&s0){snprintf((char *)Tem_H, sizeof(Tem_H), "H:      L:%2.1f", Low);LCD1602_Show_Str(0, 1, (unsigned char *)Tem_H);	LCD1602_Write_Dat(0xDF);LCD1602_Write_Dat(0x43);}else if(state==2&&s0){snprintf((char *)Tem_H, sizeof(Tem_H), "H:%2.1f  L:    ",High);LCD1602_Show_Str(0, 1, (unsigned char *)Tem_H);	LCD1602_Write_Dat(0xDF);LCD1602_Write_Dat(0x43);}else{snprintf((char *)Tem_H, sizeof(Tem_H), "H:%2.1f  L:%2.1f", High,Low);LCD1602_Show_Str(0, 1, (unsigned char *)Tem_H);	LCD1602_Write_Dat(0xDF);LCD1602_Write_Dat(0x43);			}}if(sec1!=0) sec1--;if(sec2!=0) sec2--;
}

需要原理图和全部源码的朋友可以通过下面的链接下载：
源码和原理图