[GD32E231 DIY大赛] 05. 自动喂鱼机器人之PWM篇

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[GD32E231 DIY大赛] 05. 自动喂鱼机器人之PWM篇 [复制链接]

 

[GD32E231 DIY大赛] 05. 自动喂鱼机器人之PWM篇

1.舵机基本工作原理

一般机器人控制都离不开舵机控制，这里先简单讲解一下舵机的基本工作原理：

舵机的控制信号为周期是 20ms 的脉宽调制（PWM）信号，其中脉冲宽度从 0.5ms-2.5ms，相对应舵盘的位置为 0－180 度，呈线性变化。也就是说，给它提供一定的脉宽，它的输出轴就会保持在一个相对应的角度上，无论外界转矩怎样改变，直到给它提供一个另外宽度的脉冲信号，它才会改变输出角度到新的对应的位置上。

一般而言，舵机的基准信号都是周期为20ms，宽度为1.5ms。这个基准信号定义的位置为中间位置。其中间位置的脉冲宽度是一定的，那就是1.5ms。

我是参考: https://blog.csdn.net/weixin_38075894/article/details/80027600.

20ms基准频率就是50Hz, 这个一般的单片机都是很容易生成的。

我的机械臂上的舵机型号是MG90S，是一个小舵机，机械臂是4自由度的，因此就是4个。

GD32E231的定时器功能是非常强大的，TIMER2可以同时输出四个通道的PWM，PWM可以设定不同的脉宽。

2.硬件配置

因为GD32E231start开发板，兼容arduino接口，因此我采用了arduino的转接板，转接板仅仅是转接功能，具体如下：

具体的接口配置：

PB4 TIMER2_CH0 D3 PB5 TIMER2_CH1 D4 PB0 TIMER2_CH2 D9 PB1 TIMER2_CH3 D8

3程序如下：

1. void gpio_config(void);
2. void pwm_timer_clock_enable(void);
3. void pwm_timer_config(uint32_t timer);

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1. void gpio_config(void)
2. {
3. rcu_periph_clock_enable(RCU_GPIOB);
5. /* configure PB2 output 0 */
6. gpio_mode_set(GPIOB, GPIO_MODE_OUTPUT, GPIO_PUPD_PULLUP, GPIO_PIN_2);
7. gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ,GPIO_PIN_2);
8. gpio_bit_reset(GPIOB, GPIO_PIN_2);//disable opa, ENA is connected to PB2, ENA = 0, diable opa, else, enable ENA, NOT be float
10. /* configure PB4(TIMER2 CH0) as alternate function */
11. gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_4);
12. gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ,GPIO_PIN_4);
13. gpio_af_set(GPIOB, GPIO_AF_1, GPIO_PIN_4);
15. /* configure PB5(TIMER2 CH1) as alternate function */
16. gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_5);
17. gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ,GPIO_PIN_5);
18. gpio_af_set(GPIOB, GPIO_AF_1, GPIO_PIN_5);
20. /* configure PB0(TIMER2 CH2) as alternate function */
21. gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_0);
22. gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ,GPIO_PIN_0);
23. gpio_af_set(GPIOB, GPIO_AF_1, GPIO_PIN_0);
25. /* configure PB1(TIMER2 CH3) as alternate function */
26. gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_1);
27. gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ,GPIO_PIN_1);
28. gpio_af_set(GPIOB, GPIO_AF_1, GPIO_PIN_1);
30. }

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1. /*!
2. \brief enable clock of the TIMER peripheral
3. \param[in] none
4. \param[out] none
5. \retval none
6. */
7. void pwm_timer_clock_enable()
8. {
9. rcu_periph_clock_enable(RCU_TIMER2);
10. }

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1. void pwm_timer_config(uint32_t timer)
2. {
3. /* -----------------------------------------------------------------------
4. TIMER2CLK is 100KHz
6. TIMER2 channel0 duty cycle = (25000/ 50000)* 100 = 50%
7. ----------------------------------------------------------------------- */
8. timer_oc_parameter_struct timer_ocintpara;
9. timer_parameter_struct timer_initpara;
11. timer_deinit(timer);
13. /* TIMER configuration */
14. timer_initpara.prescaler = 719;
15. timer_initpara.alignedmode = TIMER_COUNTER_EDGE;
16. timer_initpara.counterdirection = TIMER_COUNTER_UP;
17. timer_initpara.period = 1999;
18. timer_initpara.clockdivision = TIMER_CKDIV_DIV1;
19. timer_initpara.repetitioncounter = 0;
20. timer_init(timer,&timer_initpara);
22. /* configurate CH0 in PWM mode0 */
23. timer_ocintpara.ocpolarity = TIMER_OC_POLARITY_HIGH;
24. timer_ocintpara.outputstate = TIMER_CCX_ENABLE;
26. timer_channel_output_config(timer,TIMER_CH_0,&timer_ocintpara);
27. timer_channel_output_pulse_value_config(timer,TIMER_CH_0,150-1);
28. timer_channel_output_mode_config(timer,TIMER_CH_0,TIMER_OC_MODE_PWM0);
29. timer_channel_output_shadow_config(timer,TIMER_CH_0,TIMER_OC_SHADOW_DISABLE);
30. timer_auto_reload_shadow_enable(timer);
31. timer_enable(timer);
32. delay_1ms(500);
33. timer_disable(timer);
35. timer_channel_output_config(timer,TIMER_CH_1,&timer_ocintpara);
36. timer_channel_output_pulse_value_config(timer,TIMER_CH_1,150-1);
37. timer_channel_output_mode_config(timer,TIMER_CH_1,TIMER_OC_MODE_PWM0);
38. timer_channel_output_shadow_config(timer,TIMER_CH_1,TIMER_OC_SHADOW_DISABLE);
39. timer_auto_reload_shadow_enable(timer);
40. timer_enable(timer);
41. delay_1ms(500);
42. timer_disable(timer);
44. timer_channel_output_config(timer,TIMER_CH_2,&timer_ocintpara);
45. timer_channel_output_pulse_value_config(timer,TIMER_CH_2,250-1);
46. timer_channel_output_mode_config(timer,TIMER_CH_2,TIMER_OC_MODE_PWM0);
47. timer_channel_output_shadow_config(timer,TIMER_CH_2,TIMER_OC_SHADOW_DISABLE);
48. timer_auto_reload_shadow_enable(timer);
49. timer_enable(timer);
50. delay_1ms(500);
51. timer_disable(timer);
53. timer_channel_output_config(timer,TIMER_CH_3,&timer_ocintpara);
54. timer_channel_output_pulse_value_config(timer,TIMER_CH_3,160-1); //160~200, Claw form close to open
55. timer_channel_output_mode_config(timer,TIMER_CH_3,TIMER_OC_MODE_PWM0);
56. timer_channel_output_shadow_config(timer,TIMER_CH_3,TIMER_OC_SHADOW_DISABLE);
58. timer_auto_reload_shadow_enable(timer);
59. timer_enable(timer);
60. delay_1ms(500);
61. }

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然后，如果要改变特定通道的PWM宽度，可以用timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_0, value)函数.

由于舵机瞬态电流比较大，务必增大电流或者制作专用驱动电路，否则GD32E231会因为电压瞬间降低而引起复位。

我这里采用5V 3A的供电加上USB供电，并且在程序中，平滑PWM值的改变，才勉强实现系统的稳定工作。

可以采用这种法法来实现舵机平滑切换：

1. /*!
2. \brief config the specific steering motor 0,1,2,3
3. \param[in] motor_tag: 0,1,2,3; pulse: 50~250, mid=150 0.5ms~2.5ms
4. \param[out] none
5. \retval none
6. */
7. void control_motor(uint8_t motor_tag, uint32_t pulse)
8. {
9. uint8_t i;
11. if(motor_tag == 0)
12. {
13. if(pulse>=current_value[0])
14. {
15. for(i=current_value[0];i <= pulse; i++) //in case of big current to pulse MCU system
16. {
17. timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_0,i-1);
18. delay_1ms(20);
19. }
20. }
21. else
22. {
23. for(i=current_value[0];i >= pulse; i--) //in case of big current to pulse MCU system
24. {
25. timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_0,i-1);
26. delay_1ms(20);
27. }
28. }
30. current_value[0] = pulse;
31. }
32. else if (motor_tag == 1)
33. {
34. if(pulse>=current_value[1])
35. {
36. for(i=current_value[1];i <= pulse; i++) //in case of big current to pulse MCU system
37. {
38. timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_1,i-1);
39. delay_1ms(20);
40. }
41. }
42. else
43. {
44. for(i=current_value[1];i >= pulse; i--) //in case of big current to pulse MCU system
45. {
46. timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_1,i-1);
47. delay_1ms(20);
48. }
49. }
50. current_value[1] = pulse;
51. }
52. else if (motor_tag == 2)
53. {
54. if(pulse>=current_value[2])
55. {
56. for(i=current_value[2];i <= pulse; i++) //in case of big current to pulse MCU system
57. {
58. timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_2,i-1);
59. delay_1ms(30);
60. }
61. }
62. else
63. {
64. for(i=current_value[2];i >= pulse; i--) //in case of big current to pulse MCU system
65. {
66. timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_2,i-1);
67. delay_1ms(30);
68. }
69. }
70. current_value[2] = pulse;
71. }
72. else if (motor_tag == 3)
73. {
74. if(pulse>=current_value[3])
75. {
76. for(i=current_value[3];i <= pulse; i++) //in case of big current to pulse MCU system
77. {
78. timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_3,i-1);
79. delay_1ms(20);
80. }
81. }
82. else
83. {
84. for(i=current_value[3];i >= pulse; i--) //in case of big current to pulse MCU system
85. {
86. timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_3,i-1);
87. delay_1ms(50);
88. }
89. }
90. current_value[3] = pulse;
91. }
93. }

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主函数中：

1. pwm_timer_clock_enable();
2. pwm_timer_config(TIMER2);

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月下良缘

谢谢分享！

hbthgs

好资料，谢谢分享！