STM32F407测量1MHz波形频率

捕获

TIM5属于APB1时钟树，外部晶振HSE为8MHz，通过倍频给到TIM5的时钟频率为84MHz

Plain 复制代码

HSE 8MHz → PLL(M=8, N=336, P=2) → SYSCLK 168MHz
                                    ↓
                              APB1 ÷4 → PCLK1 42MHz
                                    ↓
                              TIM5 ×2 → 84MHz

初始化TIM5：开启外设时钟、GPIO 配置、时基配置、输入捕获配置、NVIC 中断配置、启动定时器

C 复制代码

GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_ICInitTypeDef TIM_ICInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_TIM5);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;
GPIO_Init(GPIOA, &GPIO_InitStructure);

TIM_TimeBaseStructure.TIM_Period = 0xFFFFFFFF;
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseInit(TIM5, &TIM_TimeBaseStructure);

TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_ICInitStructure.TIM_ICFilter = 0x03;
TIM_ICInit(TIM5, &TIM_ICInitStructure);

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
NVIC_InitStructure.NVIC_IRQChannel = TIM5_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

TIM_Cmd(TIM5, ENABLE);

TIM5时基配置，0xFFFFFFFF 是TIM5的自动重装值（ARR / Period），也就是计数器能数到的最大值

参数	值	作用
Period	0xFFFFFFFF	自动重装值设为最大，计数器从 0 数到约 51 秒才溢出（84 MHz 下）
Prescaler	0	实际分频 = 0+1 = 1，计数时钟 = 84 MHz
CounterMode	向上计数	每个时钟 +1
ClockDivision	DIV1	不影响捕获时钟，只影响采样延迟

计数中断

SQL 复制代码

void TIM5_IRQHandler(void)
{
    uint32_t cap_now;
    uint32_t period;

    if (TIM_GetITStatus(TIM5, TIM_IT_CC1) != RESET)
    {
        TIM_ClearITPendingBit(TIM5, TIM_IT_CC1);
        cap_now = TIM_GetCapture1(TIM5);

        if (s_cap_has_last)
        {
            if (cap_now >= s_cap_last)
            {
                period = cap_now - s_cap_last;
            }
            else
            {
                period = (0xFFFFFFFFu - s_cap_last) + cap_now + 1u;
            }

            if (period > 0u)
            {
                g_measured_period_ticks = period;
                g_measured_freq_hz = IC_TIM_CLK_HZ / period;
                g_capture_valid = 1;
            }

            TIM_ITConfig(TIM5, TIM_IT_CC1, DISABLE);
        }

        s_cap_last = cap_now;
        s_cap_has_last = 1;
    }
}

启动定时器捕获测量

C 复制代码

void IC_Capture_Start(void)
{
    s_cap_last = 0;
    s_cap_has_last = 0;
    TIM_SetCounter(TIM5, 0);
    TIM_ClearITPendingBit(TIM5, TIM_IT_CC1);
    TIM_ITConfig(TIM5, TIM_IT_CC1, ENABLE);
}

IC_Capture_Configuration();
IC_Capture_Start();

波形

我们用TIM14生成1MHz，TIM14和TIM5同样属于APB1总线，复用PF9引脚生成1MHz波形

C 复制代码

void TIME_Configuration(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOF, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM14, ENABLE);

    GPIO_PinAFConfig(GPIOF, GPIO_PinSource9, GPIO_AF_TIM14);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOF, &GPIO_InitStructure);

    TIM_TimeBaseStructure.TIM_Period = s_presets[0].period - 1u;
    TIM_TimeBaseStructure.TIM_Prescaler = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInit(TIM14, &TIM_TimeBaseStructure);

    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = s_presets[0].pulse;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM14, &TIM_OCInitStructure);
    TIM_OC1PreloadConfig(TIM14, TIM_OCPreload_Enable);

    TIM_ARRPreloadConfig(TIM14, ENABLE);
    TIM_Cmd(TIM14, ENABLE);

    TIME_SetFreqMode(FREQ_MODE_0P9MHZ);
}

测量

示波器

STM32串口打印