概述

本章配置GD32F303输出PWM，同时使用TIM测量PWM频率和正占空比。查阅手册可以得知，PB11为定时器1的通道3，让其输出PWM，PA6为定时器2的通道0，让作为TIM定时器输入。需要GD样片的可以加群申请：615061293 。

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生成例程

这里准备了自己绘制的开发板进行验证。

管脚图如下所示。

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keil配置

microlib 进行了高度优化以使代码变得很小。它的功能比缺省 C 库少，并且根本不具备某些 ISO C 特性。某些库函数的运行速度也比较慢，如果要使用printf(),必须开启。

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使能串口

/* 使能GPI0A，用PA9、PA10为串口 */
    rcu_periph_clock_enable(RCU_GPIOA);

    /*使能串口0的时钟 */
    rcu_periph_clock_enable(RCU_USART0);

    /*配置USARTx_Tx(PA9)为复用推挽输出*/
    gpio_init(GPIOA, GPIO_MODE_AF_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_9);

    /*配置USARTx_RxPA9)为浮空输入 */
    gpio_init(GPIOA, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_50MHZ, GPIO_PIN_10);

    /* USART 配置 */
    usart_deinit(USART0);//重置串口0
    usart_baudrate_set(USART0, 115200U);//设置串口0的波特率为115200
    usart_word_length_set(USART0, USART_WL_8BIT);          // 帧数据字长
        usart_stop_bit_set(USART0, USART_STB_1BIT);               // 停止位1位
    usart_parity_config(USART0, USART_PM_NONE);           // 无奇偶校验位
    usart_receive_config(USART0, USART_RECEIVE_ENABLE);//使能接收器
    usart_transmit_config(USART0, USART_TRANSMIT_ENABLE);//使能发送器
    usart_enable(USART0);//使能USART

串口重定向

/* retarget the C library printf function to the USART */
int fputc(int ch, FILE *f)
{
    usart_data_transmit(USART0, (uint8_t)ch);
    while(RESET == usart_flag_get(USART0, USART_FLAG_TBE));
    return ch;
}

串口重定向后就可以使用printf进行打印。

占空比与频率计算

占空比=(t1-t0)/(t2-t0) 频率=(t2-t0)/时钟频率= =(t2-t0)/(120M/(psc+1))

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周期需要2个上升沿去判断，设定第一个上升沿time_flag由0->1，下降沿time_dowm_flag由0->1，此时就知道正占空比时间，当在产生上升沿时候，就可以计算出周期使用的时间。

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GPIO初始化

/*!
    rief      configure the GPIO ports
    param[in]  none
    param[out] none
    
etval     none
*/
void gpio_configuration(void)
{
        rcu_periph_clock_enable(RCU_GPIOB);
    rcu_periph_clock_enable(RCU_GPIOA);
    rcu_periph_clock_enable(RCU_AF);

    /*configure PA6 (TIMER2 CH0) as alternate function*/
    gpio_init(GPIOA,GPIO_MODE_IN_FLOATING,GPIO_OSPEED_50MHZ,GPIO_PIN_6);
        //TIMER1-CH3
        gpio_pin_remap_config(GPIO_TIMER1_PARTIAL_REMAP1, ENABLE);
        gpio_init(GPIOB,GPIO_MODE_AF_PP,GPIO_OSPEED_50MHZ,GPIO_PIN_11);        
}

开启中断

/*!
    rief      configure the nested vectored interrupt controller
    param[in]  none
    param[out] none
    
etval     none
*/
void nvic_configuration(void)
{
    nvic_priority_group_set(NVIC_PRIGROUP_PRE1_SUB3);
    nvic_irq_enable(TIMER2_IRQn, 1, 1);
}

TIM1输出PWM初始化

PWM频率计算如下所示。

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void timer1_config(void)
{
    /* -----------------------------------------------------------------------
    TIMER1 configuration: generate 3 PWM signals with 3 different duty cycles:
    TIMER1CLK = SystemCoreClock / 120 = 1MHz

    TIMER1 channel0 duty cycle = (4000/ 16000)* 100  = 25%
    TIMER1 channel1 duty cycle = (8000/ 16000)* 100  = 50%
    TIMER1 channel2 duty cycle = (12000/ 16000)* 100 = 75%
    ----------------------------------------------------------------------- */
    timer_oc_parameter_struct timer_ocintpara;
    timer_parameter_struct timer_initpara;

    rcu_periph_clock_enable(RCU_TIMER1);

    timer_deinit(TIMER1);

    /* TIMER1 configuration */
    timer_initpara.prescaler         = 119;
    timer_initpara.alignedmode       = TIMER_COUNTER_EDGE;
    timer_initpara.counterdirection  = TIMER_COUNTER_UP;
    timer_initpara.period            = 1000;
    timer_initpara.clockdivision     = TIMER_CKDIV_DIV1;
    timer_initpara.repetitioncounter = 0;
    timer_init(TIMER1,&timer_initpara);

    /* CH0,CH1 and CH2 configuration in PWM mode */
    timer_ocintpara.outputstate  = TIMER_CCX_ENABLE;
    timer_ocintpara.outputnstate = TIMER_CCXN_DISABLE;
    timer_ocintpara.ocpolarity   = TIMER_OC_POLARITY_HIGH;
    timer_ocintpara.ocnpolarity  = TIMER_OCN_POLARITY_HIGH;
    timer_ocintpara.ocidlestate  = TIMER_OC_IDLE_STATE_LOW;
    timer_ocintpara.ocnidlestate = TIMER_OCN_IDLE_STATE_LOW;
    timer_channel_output_config(TIMER1,TIMER_CH_3,&timer_ocintpara);

    /* CH3 configuration in PWM mode0,duty cycle 50% */
    timer_channel_output_pulse_value_config(TIMER1,TIMER_CH_3,500);
    timer_channel_output_mode_config(TIMER1,TIMER_CH_3,TIMER_OC_MODE_PWM0);
    timer_channel_output_shadow_config(TIMER1,TIMER_CH_3,TIMER_OC_SHADOW_DISABLE);

    /* auto-reload preload enable */
    timer_auto_reload_shadow_enable(TIMER1);
    /* auto-reload preload enable */
    timer_enable(TIMER1);
}

TIM2输入捕获设置

void timer2_config(void)
{
    /* TIMER2 configuration: input capture mode -------------------
    the external signal is connected to TIMER2 CH0 pin (PB4)
    the rising edge is used as active edge
    the TIMER2 CH0CV is used to compute the frequency value
    ------------------------------------------------------------ */
    timer_ic_parameter_struct timer_icinitpara;
    timer_parameter_struct timer_initpara;
        //开启定时器时钟
    rcu_periph_clock_enable(RCU_TIMER2);

    timer_deinit(TIMER2);

    /* TIMER2 configuration */
    timer_initpara.prescaler         = 120-1;//定时器的时钟频率是120MHz,预分频120-1
    timer_initpara.alignedmode       = TIMER_COUNTER_EDGE;//对齐模式
    timer_initpara.counterdirection  = TIMER_COUNTER_UP;//向上计数
    timer_initpara.period            = 65535;//重载值
    timer_initpara.clockdivision     = TIMER_CKDIV_DIV1;//不分频
    timer_initpara.repetitioncounter = 0;//重复计数
    timer_init(TIMER2,&timer_initpara);

    /* TIMER2  configuration */
    /* TIMER2 CH0 input capture configuration */
    timer_icinitpara.icpolarity  = TIMER_IC_POLARITY_RISING;//捕获极性,上升沿捕获
    timer_icinitpara.icselection = TIMER_IC_SELECTION_DIRECTTI;//通道输入模式选择
    timer_icinitpara.icprescaler = TIMER_IC_PSC_DIV1;//分频
    timer_icinitpara.icfilter    = 0x0;//滤波
    timer_input_capture_config(TIMER2,TIMER_CH_0,&timer_icinitpara);

    /* auto-reload preload enable */
    timer_auto_reload_shadow_enable(TIMER2);//自动重载使能
    /* clear channel 0 interrupt bit */
    timer_interrupt_flag_clear(TIMER2,TIMER_INT_FLAG_CH0);//CH0 通道中断清除
    /* channel 0 interrupt enable */
    timer_interrupt_enable(TIMER2,TIMER_INT_CH0);//CH0 通道中断使能

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

中断

#define IR_IN1  gpio_input_bit_get (GPIOA, GPIO_PIN_6)
uint8_t time_up_flag=0;//上升沿标志位
uint8_t time_dowm_flag=0;//下降沿标志位

uint32_t time_up_num=0;//上升沿计数
uint32_t time_dowm_num=0;//下降沿计数
float time_frequency;//频率
float time_duty;//占空比


void TIMER2_IRQHandler(void)
{
            timer_ic_parameter_struct timer_icinitpara;
    timer_icinitpara.icselection = TIMER_IC_SELECTION_DIRECTTI;
    timer_icinitpara.icprescaler = TIMER_IC_PSC_DIV1;
    timer_icinitpara.icfilter    = 0x0;        
 if(SET == timer_interrupt_flag_get(TIMER2,TIMER_INT_FLAG_CH0)){
        /* clear channel 0 interrupt bit */
        timer_interrupt_flag_clear(TIMER2,TIMER_INT_FLAG_CH0);        

        if(IR_IN1&&time_up_flag==0)//第一次上升
        {
            time_up_flag=1;
            timer_icinitpara.icpolarity = TIMER_IC_POLARITY_FALLING;  //设置为下降沿
            timer_input_capture_config(TIMER2,TIMER_CH_0,&timer_icinitpara);    
            timer_counter_value_config(TIMER2 , 0); // 计数清零，从头开始计

        }
        else if(IR_IN1==0&&time_dowm_flag==0)//下降
        {

            time_dowm_num = timer_channel_capture_value_register_read(TIMER2,TIMER_CH_0)+1; // 读取捕获计数，这个时间即为上升沿持续的时间
            timer_icinitpara.icpolarity = TIMER_IC_POLARITY_RISING;  //设置为上升沿
            timer_input_capture_config(TIMER2,TIMER_CH_0,&timer_icinitpara);    
            time_dowm_flag=1;
        }        
        else if(IR_IN1&&time_dowm_flag==1)//第二次之后上升
        {        
            time_up_num = timer_channel_capture_value_register_read(TIMER2,TIMER_CH_0)+1;; // 读取捕获计数，这个时间即为上升沿持续的时间
                timer_icinitpara.icpolarity = TIMER_IC_POLARITY_FALLING;  //设置为下降沿
                timer_input_capture_config(TIMER2,TIMER_CH_0,&timer_icinitpara);
            time_dowm_flag=0;
            timer_counter_value_config(TIMER2 , 0); // 计数清零，从头开始计

        }



}

初始化

gpio_configuration(); 
    nvic_configuration();
    timer1_config();
    timer2_config();

主程序

while (1)
    {            
        time_frequency=1000000/time_up_num;//频率
        time_duty = (float)time_dowm_num/(float)time_up_num;//占空比    
        printf("
time_frequency=%.2f,time_duty=%.2f",time_frequency,time_duty*100)    ;        
        delay_1ms(1000);                            
    }