【GD32L233C-START评测】7. PWM驱动LED

hehung

【GD32L233C-START评测】7. PWM驱动LED [复制链接]

之前的帖子可以参考：

【GD32L233C-START评测】1.开箱

【GD32L233C-START评测】2.手把手创建新工程

【GD32L233C-START评测】3.移植FreeRTOS到GD32L233

【GD32L233C-START评测】4. 移植RT-Thread到GD32L233

【GD32L233C-START评测】5. IIC驱动OLED

【GD32L233C-START评测】6. 获取RTC时间并通过OLED显示

 

PWM在工程中应用比较广泛，比如LED调光明暗，电机调速，舵机控制等。

本文讲解如何使用PWM来驱动LED3和LED4。

 

一、LED接线图

LED原理图如下所示:

LED3使用的引脚为PC6，LED4使用的引脚为PC7。

 

二、引脚复用关系

查看数据手册中PC6和PC7的复用关系，

PC6复用TIMER2的CH0，PC7复用TIMER2的CH1，复用为AF1。

如下图所示：

了解到上面信息之后，可以开始进行代码编写了。

 

三、代码编辑

1. 引脚初始化

void gpio_config(void)
{
    rcu_periph_clock_enable(RCU_GPIOC);

    /*Configure PC7(TIMER2_CH1) as alternate function*/
    gpio_mode_set(GPIOC, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_7|GPIO_PIN_6);
    gpio_output_options_set(GPIOC, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_7|GPIO_PIN_6);
    gpio_af_set(GPIOC, GPIO_AF_1, GPIO_PIN_7|GPIO_PIN_6);
}

2. Timer初始化

void timer_config(void)
{
    /* TIMER2 configuration: generate PWM signals with different duty cycles:
       TIMER2CLK = SystemCoreClock / 64 = 1MHz */
    timer_oc_parameter_struct timer_ocintpara;
    timer_parameter_struct timer_initpara;

    rcu_periph_clock_enable(RCU_TIMER2);
    timer_deinit(TIMER2);

    /* TIMER2 configuration */
    timer_struct_para_init(&timer_initpara);
    timer_initpara.prescaler         = 63;
    timer_initpara.alignedmode       = TIMER_COUNTER_EDGE;
    timer_initpara.counterdirection  = TIMER_COUNTER_UP;
    timer_initpara.period            = PWM_PERIOD;
    timer_initpara.clockdivision     = TIMER_CKDIV_DIV1;
    timer_init(TIMER2, &timer_initpara);

	/* CH0 configuration in PWM mode - PC6 */
	timer_channel_output_struct_para_init(&timer_ocintpara);
    timer_ocintpara.outputstate  = TIMER_CCX_ENABLE;
    timer_ocintpara.ocpolarity   = TIMER_OC_POLARITY_HIGH;
    timer_channel_output_config(TIMER2, TIMER_CH_0, &timer_ocintpara);

    timer_channel_output_pulse_value_config(TIMER2, TIMER_CH_0, (uint32_t)(PWM_PERIOD>>1));
    timer_channel_output_mode_config(TIMER2, TIMER_CH_0, TIMER_OC_MODE_PWM0);
    timer_channel_output_shadow_config(TIMER2, TIMER_CH_0, TIMER_OC_SHADOW_DISABLE);
	
	/* CH1 configuration in PWM mode - PC7 */
    timer_channel_output_struct_para_init(&timer_ocintpara);
    timer_ocintpara.outputstate  = TIMER_CCX_ENABLE;
    timer_ocintpara.ocpolarity   = TIMER_OC_POLARITY_HIGH;
    timer_channel_output_config(TIMER2, TIMER_CH_1, &timer_ocintpara);

    timer_channel_output_pulse_value_config(TIMER2, TIMER_CH_1, (uint32_t)(PWM_PERIOD>>1));
    timer_channel_output_mode_config(TIMER2, TIMER_CH_1, TIMER_OC_MODE_PWM0);
    timer_channel_output_shadow_config(TIMER2, TIMER_CH_1, TIMER_OC_SHADOW_DISABLE);

    /* auto-reload preload enable */
    timer_auto_reload_shadow_enable(TIMER2);

    /* TIMER enable */
    timer_enable(TIMER2);
}

3.LED3和LED4 PWM驱动

void led3_pwm_ctrl(void)
{
	static int16_t i = 0;
	static uint8_t breath_flg = 0;
	
	i = (breath_flg == 0)?(i+20):(i-20);
	
	if(PWM_PERIOD < i) 
	{
		breath_flg = 1;
	}
	else if(0 >= i) 
	{
		breath_flg = 0;
	}
	/* configure TIMER channel output pulse value */
	timer_channel_output_pulse_value_config(TIMER2, TIMER_CH_0, i);
}

void led4_pwm_ctrl(void)
{
	static int16_t i = 1000;
	static uint8_t breath_flg = 1;
	
	i = (breath_flg == 0)?(i+20):(i-20);
	
	if(PWM_PERIOD < i) 
	{
		breath_flg = 1;
	}
	else if(0 >= i) 
	{
		breath_flg = 0;
	}
	/* configure TIMER channel output pulse value */
	timer_channel_output_pulse_value_config(TIMER2, TIMER_CH_1, i);
}

4.主函数

int main(void)
{
	/* configure systick */
    systick_config();

    /* configure the GPIO ports */
    gpio_config();

    /* configure the TIMER peripheral */
    timer_config();

    while(1) 
	{
        /* delay a time in milliseconds */
        delay_1ms(40);
		led3_pwm_ctrl();
		led4_pwm_ctrl();
    }
}

四、效果展示

LED3由暗到明再到暗周期显示

LED4由明到暗再到明周期显示