网上关于使用GD32单片机的ETI引脚作为计数器输入引脚的资料少之又少，此文希望有需要的朋友避免弯路。

我们把ETI引脚作为方波输入引脚，其中ETR输入引脚为PA0。通过查资料得知：

因此将先将引脚进行映射，代码如下：

void gpio_config(void)
{
    rcu_periph_clock_enable(RCU_GPIOA);
    rcu_periph_clock_enable(RCU_AF);

    /*configure PA0(TIMER1 CH0) as alternate function*/
    gpio_init(GPIOA, GPIO_MODE_AF_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_0);
    
    gpio_pin_remap_config(GPIO_TIMER1_PARTIAL_REMAP2,ENABLE);
}

然后再将时钟和中断开启即可进行输入计数了。如下代码：

void timer_config(void)
{
    /* ----------------------------------------------------------------------------
    TIMER1 Configuration:
    TIMER1 count with external clock, the prescaler is 0, the period is 1000.
    ---------------------------------------------------------------------------- */
    timer_parameter_struct timer_initpara;
    timer_ic_parameter_struct timer_icinitpara;

    rcu_periph_clock_enable(RCU_TIMER1);

    timer_deinit(TIMER1);
    /* initialize TIMER init parameter struct */
    timer_struct_para_init(&timer_initpara);
    /* TIMER1 configuration */
    timer_initpara.prescaler         = 0;
    timer_initpara.alignedmode       = TIMER_COUNTER_EDGE;
    timer_initpara.counterdirection  = TIMER_COUNTER_UP;
    timer_initpara.period            = 999;
    timer_initpara.clockdivision     = TIMER_CKDIV_DIV1;
    timer_init(TIMER1, &timer_initpara);

    /* TIMER1 CH0 input capture configuration */
    timer_icinitpara.icpolarity  = TIMER_IC_POLARITY_RISING;
    timer_icinitpara.icselection = TIMER_IC_SELECTION_DIRECTTI;
    timer_icinitpara.icprescaler = TIMER_IC_PSC_DIV1;
    timer_icinitpara.icfilter    = 0x01;
    timer_input_capture_config(TIMER1, TIMER_CH_0, &timer_icinitpara);

    /* slave mode selection : TIMER1 */
    /* TIMER1 input trigger : external trigger connected to CI0 */
    timer_input_trigger_source_select(TIMER1,TIMER_SMCFG_TRGSEL_CI0FE0);
    timer_slave_mode_select(TIMER1,TIMER_SLAVE_MODE_EXTERNAL0);
    
    /* enable the TIMER interrupt */
    timer_interrupt_flag_clear(TIMER1, TIMER_INT_FLAG_UP);
    timer_interrupt_enable(TIMER1, TIMER_INT_UP);
    
    timer_enable(TIMER1);
}

开启中断：

void nvic_config(void)
{
    nvic_priority_group_set(NVIC_PRIGROUP_PRE1_SUB3);
    nvic_irq_enable(TIMER1_IRQn, 1, 1);
}
 

具体的例子如下，可进行下载：

https://download.csdn.net/download/xiaoyaofriend/89514393