【Ai-M61-32SU入门】学习PWM的使用

这次来学习一下PWM的用法，从手册中可以看到BL616/BL618有一个PWM生成器支持4组通道


下面用RGB灯珠通过PWM实现红绿蓝的呼吸效果，在手册上找到IO对应的IO通道


代码实现

1. #include "bflb_gpio.h"
   
2. #include "bflb_mtimer.h"
   
3. #include "bflb_pwm_v2.h"
   
4. #include "bflb_clock.h"
   
5. #include "board.h"
   
6. #include "bl616_glb.h"
   
7. 
   
8. struct bflb_device_s *gpio;
   
9. struct bflb_device_s *pwm;
   
10. uint8_t rgb_pwmchs[3] = {0};
    
11. uint8_t rgb_index = 0;
    
12. uint16_t rgb_pwm = 0;
    
13. 
    
14. int main(void)
    
15. {
    
16.     board_init();
    
17.     gpio = bflb_device_get_by_name("gpio");
    
18.     pwm = bflb_device_get_by_name("pwm_v2_0");
    
19.     bflb_gpio_init(gpio, GPIO_PIN_12, GPIO_FUNC_PWM0 | GPIO_ALTERNATE | GPIO_FLOAT | GPIO_SMT_EN | GPIO_DRV_1); //R CH0P CH2P
    
20.     bflb_gpio_init(gpio, GPIO_PIN_14, GPIO_FUNC_PWM0 | GPIO_ALTERNATE | GPIO_FLOAT | GPIO_SMT_EN | GPIO_DRV_1); //G CH2P CH3P
    
21.     bflb_gpio_init(gpio, GPIO_PIN_15, GPIO_FUNC_PWM0 | GPIO_ALTERNATE | GPIO_FLOAT | GPIO_SMT_EN | GPIO_DRV_1); //B CH3P CH3N
    
22.     struct bflb_pwm_v2_config_s cfg = {
    
23.         .clk_source = BFLB_SYSTEM_XCLK,
    
24.         .clk_div = 40,
    
25.         .period = 1000,
    
26.     };
    
27.     bflb_pwm_v2_init(pwm, &cfg);
    
28.     bflb_pwm_v2_channel_positive_start(pwm, PWM_CH0);
    
29.     bflb_pwm_v2_channel_positive_start(pwm, PWM_CH2);
    
30.     bflb_pwm_v2_channel_positive_start(pwm, PWM_CH3);
    
31.     bflb_pwm_v2_start(pwm);
    
32.     rgb_pwmchs[0] = PWM_CH0;
    
33.     rgb_pwmchs[1] = PWM_CH2;
    
34.     rgb_pwmchs[2] = PWM_CH3;
    
35.     while (1) {
    
36.         if(rgb_pwm > 1999)
    
37.         {
    
38.             rgb_index += 1;
    
39.             rgb_pwm = 0;
    
40.             if(rgb_index > 2)
    
41.                 rgb_index = 0;
    
42.         }
    
43.         rgb_pwm += 1;
    
44.         if(rgb_pwm>1000)
    
45.         {
    
46.             bflb_pwm_v2_channel_set_threshold(pwm, rgb_pwmchs[rgb_index], 0, 2000 - rgb_pwm);
    
47.         }
    
48.         else
    
49.         {
    
50.             bflb_pwm_v2_channel_set_threshold(pwm, rgb_pwmchs[rgb_index], 0, rgb_pwm);
    
51.         }
    
52.         bflb_mtimer_delay_ms(1);
    
53.     }
    
54. }

复制代码

代码解析：
bflb_device_get_by_name("pwm_v2_0") BL616/BL618只支持PWM_V2，外设支持情况可以看这张图


clk_source = BFLB_SYSTEM_XCLK 设置PWM的时钟源，可以选择bclk、 xclk、 f32k
clk_div = 40 时钟分频，最大65535，0和1都是不分频
period = 1000 PWM 周期 = PWM 源时钟 / pwm_clk_div / pwm_period
bflb_pwm_v2_init(pwm, &cfg) 以指定的参数初始化PWM
bflb_pwm_v2_channel_positive_start 开启正向通道(CHxP)输出，与之相对的是bflb_pwm_v2_channel_negative_start开启负向通道(CHxN)
bflb_pwm_v2_start 开启PWM
bflb_pwm_v2_channel_set_threshold 设置占空比，默认情况下当计数值在第3个参数和第4个参数间时正向通道输出高电平，反之输出低电平
运行效果


上面的示例只用到了正向输出通道，每一路通道还有互补输出，例如G和B就是通道3的互补输出，R和C是通道2的互补输出，为了拍摄看得明显些这里选择R和C，要使用负向通道的话需要用GLB_Set_PWM1_IO_Sel改变PWM的外设选择，代码示例

1. #include "bflb_gpio.h"
   
2. #include "bflb_mtimer.h"
   
3. #include "bflb_pwm_v2.h"
   
4. #include "bflb_clock.h"
   
5. #include "board.h"
   
6. #include "bl616_glb.h"
   
7. 
   
8. struct bflb_device_s *gpio;
   
9. struct bflb_device_s *pwm;
   
10. uint16_t rgb_pwm = 0;
    
11. 
    
12. int main(void)
    
13. {
    
14.     board_init();
    
15.     GLB_Set_PWM1_IO_Sel(GLB_PWM1_IO_DIFF_END);
    
16.     gpio = bflb_device_get_by_name("gpio");
    
17.     pwm = bflb_device_get_by_name("pwm_v2_0");
    
18.     bflb_gpio_init(gpio, GPIO_PIN_12, GPIO_FUNC_PWM0 | GPIO_ALTERNATE | GPIO_FLOAT | GPIO_SMT_EN | GPIO_DRV_1); //R CH0P CH2P
    
19.     bflb_gpio_init(gpio, GPIO_PIN_29, GPIO_FUNC_PWM0 | GPIO_ALTERNATE | GPIO_FLOAT | GPIO_SMT_EN | GPIO_DRV_1); //R CH1P CH2N
    
20.     struct bflb_pwm_v2_config_s cfg = {
    
21.         .clk_source = BFLB_SYSTEM_XCLK,
    
22.         .clk_div = 40,
    
23.         .period = 1000,
    
24.     };
    
25.     bflb_pwm_v2_init(pwm, &cfg);
    
26.     bflb_pwm_v2_channel_positive_start(pwm, PWM_CH2);
    
27.     bflb_pwm_v2_channel_negative_start(pwm, PWM_CH2);
    
28.     bflb_pwm_v2_start(pwm);
    
29.     while (1) {
    
30.         if(rgb_pwm > 1999)
    
31.         {
    
32.             rgb_pwm = 0;
    
33.         }
    
34.         rgb_pwm += 1;
    
35.         if(rgb_pwm>1000)
    
36.         {
    
37.             bflb_pwm_v2_channel_set_threshold(pwm, PWM_CH2, 0, 2000 - rgb_pwm);
    
38.         }
    
39.         else
    
40.         {
    
41.             bflb_pwm_v2_channel_set_threshold(pwm, PWM_CH2, 0, rgb_pwm);
    
42.         }
    
43.         bflb_mtimer_delay_ms(1);
    
44.     }
    
45. }

复制代码

运行效果，只控制1个通道的占空比就能让2个LED交替呼吸

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