单片机输出pwm波在项目中是恨常用的一个功能，今天就总结一下用STM32F103C8T6单片机输出16路 pwm波。

使用keil5软件，用标准库函数来实现。

首先看定时器初始化

1. void TIM1_PWM_Init(u16 arr, u16 psc)
   
2. {
   
3.     GPIO_InitTypeDef GPIO_InitStructure;
   
4.     TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
   
5.     TIM_OCInitTypeDef TIM_OCInitSturcture;
   
6. 
   
7.     RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_TIM1, ENABLE);
   
8.     //初始化IO口
   
9.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 | GPIO_Pin_11;
   
10.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    
11.     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    
12.     GPIO_Init(GPIOA, &GPIO_InitStructure);
    
13. 
    
14.     //设置 TIM ARR PSC
    
15.     TIM_TimeBaseInitStructure.TIM_Period = arr;
    
16.     TIM_TimeBaseInitStructure.TIM_Prescaler = psc;
    
17.     TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    
18.     TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;                //向上计数模式
    
19.     TIM_TimeBaseInitStructure.TIM_RepetitionCounter = 0x00;
    
20.     TIM_TimeBaseInit(TIM1, &TIM_TimeBaseInitStructure);
    
21. 
    
22.     //TIM1_CH1  PWM1 模式
    
23.     TIM_OCInitSturcture.TIM_OCMode = TIM_OCMode_PWM1;
    
24.     TIM_OCInitSturcture.TIM_OutputState = TIM_OutputState_Enable;
    
25.     TIM_OCInitSturcture.TIM_OCPolarity = TIM_OCPolarity_High;                        //输出高电平有效
    
26.     TIM_OC1Init(TIM1, &TIM_OCInitSturcture);
    
27. 
    
28.     //TIM1_CH2  PWM1 模式
    
29.     TIM_OCInitSturcture.TIM_OCMode = TIM_OCMode_PWM1;
    
30.     TIM_OCInitSturcture.TIM_OutputState = TIM_OutputState_Enable;
    
31.     TIM_OCInitSturcture.TIM_OCPolarity = TIM_OCPolarity_High;                 
    
32.     TIM_OC2Init(TIM1, &TIM_OCInitSturcture);
    
33. 
    
34. 
    
35.     //TIM1_CH3  PWM2 模式
    
36.     TIM_OCInitSturcture.TIM_OCMode = TIM_OCMode_PWM1;
    
37.     TIM_OCInitSturcture.TIM_OutputState = TIM_OutputState_Enable;
    
38.     TIM_OCInitSturcture.TIM_OCPolarity = TIM_OCPolarity_High;                 
    
39.     TIM_OC3Init(TIM1, &TIM_OCInitSturcture);
    
40. 
    
41.     //TIM1_CH4  PWM2 模式
    
42.     TIM_OCInitSturcture.TIM_OCMode = TIM_OCMode_PWM1;
    
43.     TIM_OCInitSturcture.TIM_OutputState = TIM_OutputState_Enable;
    
44.     TIM_OCInitSturcture.TIM_OCPolarity = TIM_OCPolarity_High;               
    
45.     TIM_OC4Init(TIM1, &TIM_OCInitSturcture);
    
46. 
    
47. 
    
48.     TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Enable);                                        //TIM1_CH1 使能预装载寄存器
    
49.     TIM_OC2PreloadConfig(TIM1, TIM_OCPreload_Enable);                                         //TIM1_CH2 使能预装载寄存器
    
50.     TIM_OC3PreloadConfig(TIM1, TIM_OCPreload_Enable);                                         //TIM1_CH3 使能预装载寄存器
    
51.     TIM_OC4PreloadConfig(TIM1, TIM_OCPreload_Enable);                                         //TIM1_CH4 使能预装载寄存器
    
52. 
    
53. 
    
54.     TIM_Cmd(TIM1, ENABLE);                                //使能计数器
    
55.     TIM_CtrlPWMOutputs(TIM1, ENABLE);        //主输出使能
    
56. }

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初始化定时1的4个通道，对应IO口为 PA8，PA9，PA10，PA11,将这4个口都设置为PWM输出口。入口参数arr用来设置定时器的自动重装载值，psc用于设置时钟分频系数。时钟默认为72MHZ。

下来初始化定时器2

1. void TIM2_PWM_Init(u16 arr, u16 psc)
   
2. {
   
3.     GPIO_InitTypeDef GPIO_InitStructure;
   
4.     TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
   
5.     TIM_OCInitTypeDef TIM_OCInitStructure;
   
6. 
   
7.     RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);                          //使能定时器2时钟
   
8.     RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA , ENABLE);                  //使能GPIO时钟
   
9. 
   
10.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
    
11.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    
12.     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    
13.     GPIO_Init(GPIOA, &GPIO_InitStructure);
    
14. 
    
15.     //初始化TIM2
    
16.     TIM_TimeBaseInitStructure.TIM_Period = arr;
    
17.     TIM_TimeBaseInitStructure.TIM_Prescaler = psc;
    
18.     TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    
19.     TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    
20.     TIM_TimeBaseInit(TIM2, &TIM_TimeBaseInitStructure);
    
21. 
    
22.         //初始化TIM2_CH1  PWM 模式
    
23.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
24.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
25.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
26.     TIM_OC1Init(TIM2, &TIM_OCInitStructure);        
    
27. 
    
28.     //初始化TIM2_CH2  PWM 模式
    
29.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
30.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
31.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
32.     TIM_OC2Init(TIM2, &TIM_OCInitStructure);
    
33. 
    
34.     //初始化TIM2_CH3  PWM 模式
    
35.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
36.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
37.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
38.     TIM_OC3Init(TIM2, &TIM_OCInitStructure);
    
39. 
    
40.     //初始化TIM2_CH4  PWM 模式
    
41.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
42.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
43.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
44.     TIM_OC4Init(TIM2, &TIM_OCInitStructure);
    
45. 
    
46.     //使能TIM2在CCR上的预装载寄存器
    
47.         TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Enable);
    
48.     TIM_OC2PreloadConfig(TIM2, TIM_OCPreload_Enable);
    
49.     TIM_OC3PreloadConfig(TIM2, TIM_OCPreload_Enable);
    
50.     TIM_OC4PreloadConfig(TIM2, TIM_OCPreload_Enable);
    
51. 
    
52.     //使能TIM2
    
53.     TIM_Cmd(TIM2, ENABLE);
    
54. }

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这里要注意的是，定时器1是高级定时器，定时器2、3、4是通用定时器。只有高级定时器有重复计数寄存器，而通过定时器没有重复计数寄存器。定时器2初始化时，比定时器1少一行代码，这里要注意一下。

1. TIM_TimeBaseInitStructure.TIM_RepetitionCounter = 0x00;

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重复计数寄存器主要作用如下：



其余设置方法和定时器1基本一样，定时器2的4个通道对应的IO口为PA0，PA1，PA2，PA3.将这四个口设置为PWM输出模式。

入口参数arr用来设置定时器的自动重装载值，psc用于设置时钟分频系数。时钟默认为72MHZ。

下来设置定时器3

1. void TIM3_PWM_Init(u16 arr, u16 psc)
   
2. {
   
3.     GPIO_InitTypeDef GPIO_InitStructure;
   
4.     TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
   
5.     TIM_OCInitTypeDef TIM_OCInitStructure;
   
6. 
   
7.     RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);                                                        //使能定时器3时钟
   
8.     RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB, ENABLE);        //使能GPIO时钟
   
9. 
   
10.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
    
11.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    
12.     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    
13.     GPIO_Init(GPIOA, &GPIO_InitStructure);
    
14. 
    
15.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
    
16.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    
17.     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    
18.     GPIO_Init(GPIOB, &GPIO_InitStructure);
    
19. 
    
20.     //初始化TIM3
    
21.     TIM_TimeBaseInitStructure.TIM_Period = arr;
    
22.     TIM_TimeBaseInitStructure.TIM_Prescaler = psc;
    
23.     TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    
24.     TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    
25.     TIM_TimeBaseInit(TIM3, &TIM_TimeBaseInitStructure);
    
26. 
    
27.     //初始化TIM3_CH1  PWM 模式
    
28.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
29.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
30.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
31.     TIM_OC1Init(TIM3, &TIM_OCInitStructure);
    
32. 
    
33.     //初始化TIM3_CH2  PWM 模式
    
34.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
35.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
36.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
37.     TIM_OC2Init(TIM3, &TIM_OCInitStructure);
    
38. 
    
39.     //初始化TIM3_CH3  PWM 模式
    
40.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
41.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
42.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
43.     TIM_OC3Init(TIM3, &TIM_OCInitStructure);
    
44. 
    
45.     //初始化TIM3_CH4  PWM 模式
    
46.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
47.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
48.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
49.     TIM_OC4Init(TIM3, &TIM_OCInitStructure);
    
50. 
    
51.     //使能TIM3在CCR上的预装载寄存器
    
52.     TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);
    
53.     TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);
    
54.     TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);
    
55.     TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);
    
56.     //使能TIM3
    
57.     TIM_Cmd(TIM3, ENABLE);
    
58. }

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设置方法和定时器2一样，定时器3的4个通道对应的IO口为PA6，PA7，PB0，PB1。将这四个口设置为PWM输出模式。

入口参数arr用来设置定时器的自动重装载值，psc用于设置时钟分频系数。时钟默认为72MHZ。

最后设置定时器4

1. 
   
2. void TIM4_PWM_Init(u16 arr, u16 psc)
   
3. {
   
4.     GPIO_InitTypeDef GPIO_InitStructure;
   
5.     TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
   
6.     TIM_OCInitTypeDef TIM_OCInitStructure;
   
7. 
   
8.     RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);                        //使能定时器4时钟
   
9.     RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB , ENABLE);                  //使能GPIO时钟
   
10. 
    
11.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9;
    
12.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    
13.     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    
14.     GPIO_Init(GPIOB, &GPIO_InitStructure);
    
15. 
    
16. 
    
17.     //初始化TIM4
    
18.     TIM_TimeBaseInitStructure.TIM_Period = arr;
    
19.     TIM_TimeBaseInitStructure.TIM_Prescaler = psc;
    
20.     TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    
21.     TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    
22.     TIM_TimeBaseInit(TIM4, &TIM_TimeBaseInitStructure);
    
23. 
    
24.         //初始化TIM4_CH1  PWM 模式
    
25.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
26.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
27.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
28.     TIM_OC1Init(TIM4, &TIM_OCInitStructure);
    
29.         
    
30. 
    
31.     //初始化TIM4_CH2  PWM 模式
    
32.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
33.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
34.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
35.     TIM_OC2Init(TIM4, &TIM_OCInitStructure);
    
36. 
    
37.     //初始化TIM4_CH3  PWM 模式
    
38.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
39.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
40.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
41.     TIM_OC3Init(TIM4, &TIM_OCInitStructure);
    
42. 
    
43.     //初始化TIM4_CH4  PWM 模式
    
44.     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
45.     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    
46.     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
47.     TIM_OC4Init(TIM4, &TIM_OCInitStructure);
    
48. 
    
49.     //使能TIM4在CCR上的预装载寄存器
    
50.     TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable);
    
51.     TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable);
    
52.     TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Enable);
    
53.     TIM_OC4PreloadConfig(TIM4, TIM_OCPreload_Enable);
    
54. 
    
55.     //使能TIM4
    
56.     TIM_Cmd(TIM4, ENABLE);
    
57. }

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设置方法和定时器2一样，定时器4的4个通道对应的IO口为PB6，PB7，PB8，PB9。将这四个口设置为PWM输出模式。

入口参数arr用来设置定时器的自动重装载值，psc用于设置时钟分频系数。时钟默认为72MHZ。

这样总共16路的PWM初始化就完成了，下来看主函数设置

1. #include "sys.h"
   
2. #include "delay.h"
   
3. #include "usart.h"
   
4. #include "pwm.h"
   
5. 
   
6. int main(void)
   
7. {
   
8.     u16 led_pwm_val = 0;
   
9. 
   
10.     delay_init();       //延时函数初始化
    
11.     NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
    
12. 
    
13.     //不分频。PWM频率=72000000/9000=8Khz
    
14.     TIM1_PWM_Init(8999, 0);
    
15.     TIM2_PWM_Init(8999, 0);
    
16.     TIM3_PWM_Init(8999, 0);
    
17.     TIM4_PWM_Init(8999, 0);
    
18.     led_pwm_val = 899;
    
19.     while(1)
    
20.     {
    
21.         if(led_pwm_val < 8999)
    
22.             led_pwm_val++;
    
23.         else
    
24.             led_pwm_val = 0;
    
25. 
    
26.         TIM_SetCompare1(TIM1, led_pwm_val);                            //TIM1_CH1    PA8
    
27.         TIM_SetCompare2(TIM1, led_pwm_val);                                //TIM1_CH2    PA9
    
28.         TIM_SetCompare3(TIM1, led_pwm_val);                                //TIM1_CH3    PA10
    
29.         TIM_SetCompare4(TIM1, led_pwm_val);                                //TIM1_CH4    PA11
    
30. 
    
31.         TIM_SetCompare1(TIM2, led_pwm_val);                                //TIM2_CH1          PA0
    
32.         TIM_SetCompare2(TIM2, led_pwm_val);                                //TIM2_CH2    PA1
    
33.         TIM_SetCompare3(TIM2, led_pwm_val);                                //TIM2_CH3    PA2
    
34.         TIM_SetCompare4(TIM2, led_pwm_val);                                //TIM2_CH4    PA3
    
35. 
    
36.         TIM_SetCompare1(TIM3, led_pwm_val);                           //TIM3_CH1          PA6
    
37.         TIM_SetCompare2(TIM3, led_pwm_val);                                //TIM3_CH2    PA7
    
38.         TIM_SetCompare3(TIM3, led_pwm_val);                                //TIM3_CH3    PB0
    
39.         TIM_SetCompare4(TIM3, led_pwm_val);                                //TIM3_CH4    PB1
    
40. 
    
41.         TIM_SetCompare1(TIM4, led_pwm_val);                                //TIM4_CH1     PB6
    
42.         TIM_SetCompare2(TIM4, led_pwm_val);                                //TIM4_CH2     PB7
    
43.         TIM_SetCompare3(TIM4, led_pwm_val);                                //TIM4_CH3     PB8
    
44.         TIM_SetCompare4(TIM4, led_pwm_val);                                //TIM4_CH4     PB9
    
45. 
    
46.         delay_ms(1);
    
47.     }
    
48. }
    

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初始化时设置4个定时器的频率为8K，在while循环中调节占空比从0---100%变化。程序编译后烧写到单片机中，通过示波器就能观察到PWM波形变化了。

这里先用软件仿真看一下效果