【实验】使用定时器的外部时钟模式对多谐振荡器的性能进行评估_STM32吧

12楼 巨大八爪鱼 2017-4-2 14:42

几次脉冲总长度（=高电平时间+低电平时间）数据：
0.7611s
0.7593s
0.7583s
0.7596s
0.7590s
0.7595s
0.7586s
几次高电平长度数据：
0.3602s
0.3575s
0.3593s
0.3594s
0.3582s

13楼 巨大八爪鱼 2017-4-2 15:37

【将测量结果通过串口发送到电脑上，方便复制】
#include <stm32f10x.h>
#include <string.h>

const uint8_t seg8[] = {0xc0, 0xf9, 0xa4, 0xb0, 0x99, 0x92, 0x82, 0xf8, 0x80, 0x90};
char str[] = "Total: x.xxxxs High Level: x.xxxxs\r\n";

void delay(void)
{
    uint16_t i;
    for (i = 0; i < 20000; i++);
}

void ser_in(uint8_t data)
{
    uint8_t i;
    for (i = 0; i < 8; i++)
    {
        GPIO_ResetBits(GPIOB, GPIO_Pin_9); // SCLK=>PB9
        if (data & 0x80)
            GPIO_SetBits(GPIOB, GPIO_Pin_7); // DIO=>PB7
        else
            GPIO_ResetBits(GPIOB, GPIO_Pin_7);
        data <<= 1;
        GPIO_SetBits(GPIOB, GPIO_Pin_9);
    }
}

void par_out(void)
{
    GPIO_ResetBits(GPIOB, GPIO_Pin_8); // RCLK=>PB8
    GPIO_SetBits(GPIOB, GPIO_Pin_8);
}

void seg_scan(void)
{
    uint16_t numbuf;
    uint8_t i;
    if (GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_1) == SET)
        numbuf = TIM_GetCapture1(TIM2); // 按键松开时显示上次脉冲的总长度(单位: 秒)
    else
        numbuf = TIM_GetCapture2(TIM2); // 按键按下时显示高电平的长度(单位: 秒)
    for (i = 0; i < 5; i++)
    {
        __disable_irq();
        if (i == 4)
            ser_in(seg8[numbuf % 10] & 0x7f); // 显示小数点
        else
            ser_in(seg8[numbuf % 10]);
        ser_in(1 << i);
        par_out();
        __enable_irq();
        delay();
        numbuf /= 10;
    }
}

int main(void)
{
    DMA_InitTypeDef dma;
    GPIO_InitTypeDef gpio;
    NVIC_InitTypeDef nvic;
    TIM_ICInitTypeDef timic;
    TIM_TimeBaseInitTypeDef tim;
    USART_InitTypeDef usart;

    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB | RCC_APB2Periph_GPIOC | RCC_APB2Periph_USART1, ENABLE);

    // 时钟输入引脚和串口接收引脚配置
    gpio.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    gpio.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_10;
    GPIO_Init(GPIOA, &gpio);

    // 串口发送引脚配置
    gpio.GPIO_Mode = GPIO_Mode_AF_PP;
    gpio.GPIO_Pin = GPIO_Pin_9;
    gpio.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &gpio);

    // 数码管扫描管脚配置
    gpio.GPIO_Mode = GPIO_Mode_Out_PP;
    gpio.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9;
    gpio.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &gpio);

    // 按键管脚PC1配置
    gpio.GPIO_Mode = GPIO_Mode_IPU;
    gpio.GPIO_Pin = GPIO_Pin_1;
    GPIO_Init(GPIOC, &gpio);

    // 配置定时器的计数范围
    TIM_TimeBaseStructInit(&tim);
    tim.TIM_CounterMode = TIM_CounterMode_Up;
    tim.TIM_Period = 0xffff; // 最大计数值
    tim.TIM_Prescaler = 7199; // 7200分频, 得到基准时钟0.1ms
    TIM_TimeBaseInit(TIM2, &tim);

    // 配置定时器2的通道1
    timic.TIM_Channel = TIM_Channel_1;
    timic.TIM_ICFilter = 0; // 不消抖
    timic.TIM_ICPolarity = TIM_ICPolarity_Rising; // 通道1捕获上升沿
    timic.TIM_ICPrescaler = TIM_ICPSC_DIV1;
    timic.TIM_ICSelection = TIM_ICSelection_DirectTI; // TI1->IC1=PA0
    TIM_ICInit(TIM2, &timic);

    // 配置定时器2的通道2
    timic.TIM_Channel = TIM_Channel_2;
    timic.TIM_ICFilter = 0;
    timic.TIM_ICPolarity = TIM_ICPolarity_Falling; // 通道2捕获下降沿
    timic.TIM_ICPrescaler = TIM_ICPSC_DIV1;
    timic.TIM_ICSelection = TIM_ICSelection_IndirectTI; // TI2->IC1=PA0
    TIM_ICInit(TIM2, &timic);

    TIM_SelectInputTrigger(TIM2, TIM_TS_TI1FP1); // TRGI=TI1
    TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset); // 上升沿使定时器归0
    TIM_Cmd(TIM2, ENABLE);

    // 配置串口
    USART_StructInit(&usart);
    usart.USART_BaudRate = 115200;
    usart.USART_Mode = USART_Mode_Tx;
    USART_Init(USART1, &usart);
    USART_Cmd(USART1, ENABLE);

    // 配置串口DMA
    USART_DMACmd(USART1, USART_DMAReq_Tx, ENABLE);
    dma.DMA_BufferSize = 0;
    dma.DMA_DIR = DMA_DIR_PeripheralDST;
    dma.DMA_M2M = DMA_M2M_Disable;
    dma.DMA_MemoryBaseAddr = (uint32_t)str;
    dma.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    dma.DMA_MemoryInc = DMA_MemoryInc_Enable;
    dma.DMA_Mode = DMA_Mode_Normal;
    dma.DMA_PeripheralBaseAddr = (uint32_t)&USART1->DR;
    dma.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    dma.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    dma.DMA_Priority = DMA_Priority_Low;
    DMA_Init(DMA1_Channel4, &dma);

    // 配置定时器中断
    TIM_ITConfig(TIM2, TIM_IT_Trigger, ENABLE);
    nvic.NVIC_IRQChannel = TIM2_IRQn;
    nvic.NVIC_IRQChannelCmd = ENABLE;
    nvic.NVIC_IRQChannelPreemptionPriority = 0;
    nvic.NVIC_IRQChannelSubPriority = 0;
    NVIC_Init(&nvic);

    while (1)
        seg_scan();
}

void TIM2_IRQHandler(void)
{
    uint8_t i, j;
    uint16_t numbuf;
    TIM_ClearITPendingBit(TIM2, TIM_IT_Trigger);
    for (i = 7; i < 30; i += 21)
    {
        if (i == 7)
            numbuf = TIM_GetCapture1(TIM2);
        else
            numbuf = TIM_GetCapture2(TIM2);
        for (j = 5; j <= 5; j--)
        {
            if (j == 1)
                continue;
            str[i + j] = '0' + numbuf % 10;
            numbuf /= 10;
        }
    }
    DMA_Cmd(DMA1_Channel4, DISABLE);
    DMA_SetCurrDataCounter(DMA1_Channel4, strlen(str));
    DMA_Cmd(DMA1_Channel4, ENABLE);
}

14楼 巨大八爪鱼 2017-4-2 15:38

【测得的数据】
Total: 0.0519s High Level: 0.0000s
Total: 0.7598s High Level: 0.3597s
Total: 0.7676s High Level: 0.3614s
Total: 0.7684s High Level: 0.3618s
Total: 0.7688s High Level: 0.3635s
Total: 0.7653s High Level: 0.3630s
Total: 0.7654s High Level: 0.3606s
Total: 0.7639s High Level: 0.3617s
Total: 0.7643s High Level: 0.3592s
Total: 0.7602s High Level: 0.3556s
Total: 0.7624s High Level: 0.3595s
Total: 0.7605s High Level: 0.3587s
Total: 0.7571s High Level: 0.3535s
Total: 0.7599s High Level: 0.3567s
Total: 0.7605s High Level: 0.3572s
Total: 0.7566s High Level: 0.3520s
Total: 0.7593s High Level: 0.3547s
Total: 0.7553s High Level: 0.3543s
Total: 0.7537s High Level: 0.3493s
Total: 0.7555s High Level: 0.3542s
Total: 0.7562s High Level: 0.3532s
Total: 0.7601s High Level: 0.3570s
Total: 0.7526s High Level: 0.3523s
Total: 0.7596s High Level: 0.3577s
Total: 0.7576s High Level: 0.3553s
Total: 0.7571s High Level: 0.3537s
Total: 0.7537s High Level: 0.3542s
Total: 0.7585s High Level: 0.3560s
Total: 0.7562s High Level: 0.3522s
Total: 0.7548s High Level: 0.3541s
Total: 0.7539s High Level: 0.3499s
Total: 0.7534s High Level: 0.3514s
Total: 0.7565s High Level: 0.3526s
Total: 0.7538s High Level: 0.3522s
Total: 0.7582s High Level: 0.3560s
Total: 0.7521s High Level: 0.3509s
Total: 0.7551s High Level: 0.3516s
Total: 0.7515s High Level: 0.3493s
Total: 0.7538s High Level: 0.3527s
Total: 0.7498s High Level: 0.3497s
Total: 0.7565s High Level: 0.3545s
Total: 0.7529s High Level: 0.3523s
Total: 0.7493s High Level: 0.3488s
Total: 0.7500s High Level: 0.3498s
Total: 0.7569s High Level: 0.3547s
Total: 0.7521s High Level: 0.3511s
Total: 0.7496s High Level: 0.3492s
Total: 0.7502s High Level: 0.3498s
Total: 0.7572s High Level: 0.3550s
Total: 0.7522s High Level: 0.3519s
Total: 0.7551s High Level: 0.3512s
Total: 0.7495s High Level: 0.3463s
Total: 0.7535s High Level: 0.3522s
Total: 0.7517s High Level: 0.3514s
Total: 0.7499s High Level: 0.3500s
Total: 0.7503s High Level: 0.3504s
Total: 0.7543s High Level: 0.3504s
Total: 0.7543s High Level: 0.3535s

15楼 巨大八爪鱼 2017-4-2 15:45

【TIM2_IRQHandler函数容错处理】
// 仅当上次发送完毕后再发送新内容, 否则丢弃本次测量结果
if (DMA_GetCurrDataCounter(DMA1_Channel4) == 0)
{
    DMA_Cmd(DMA1_Channel4, DISABLE);
    DMA_SetCurrDataCounter(DMA1_Channel4, strlen(str));
    DMA_Cmd(DMA1_Channel4, ENABLE);
}

16楼 巨大八爪鱼 2017-4-2 15:46

【将左LED灯短路后测得的数据】
Total: 0.2129s High Level: 0.0011s
Total: 0.0042s High Level: 0.0022s
Total: 0.0066s High Level: 0.0009s
Total: 0.4424s High Level: 0.4061s
Total: 0.4432s High Level: 0.4025s
Total: 0.0032s High Level: 0.0006s
Total: 0.4497s High Level: 0.4123s
Total: 0.4442s High Level: 0.0000s
Total: 0.0029s High Level: 0.0008s
Total: 0.4509s High Level: 0.4147s
Total: 0.4501s High Level: 0.4133s
Total: 0.0049s High Level: 0.0049s
Total: 0.4339s High Level: 0.3970s
Total: 0.4497s High Level: 0.4138s
Total: 0.4507s High Level: 0.4138s
Total: 0.4589s High Level: 0.4210s
Total: 0.4336s High Level: 0.0020s
Total: 0.0033s High Level: 0.0010s
Total: 0.4332s High Level: 0.4002s
Total: 0.0051s High Level: 0.0033s
Total: 0.4352s High Level: 0.4035s
Total: 0.0057s High Level: 0.0032s
Total: 0.4301s High Level: 0.3939s
Total: 0.4495s High Level: 0.4122s
Total: 0.4494s High Level: 0.4133s
Total: 0.4509s High Level: 0.4145s
Total: 0.4489s High Level: 0.4128s
Total: 0.4388s High Level: 0.4025s
Total: 0.4503s High Level: 0.4142s
Total: 0.4394s High Level: 0.4033s
Total: 0.4498s High Level: 0.4123s
Total: 0.4489s High Level: 0.4118s
Total: 0.4495s High Level: 0.4122s
Total: 0.4402s High Level: 0.4039s
Total: 0.4500s High Level: 0.4129s
Total: 0.4530s High Level: 0.4191s
Total: 0.4564s High Level: 0.4200s
Total: 0.4389s High Level: 0.4026s
Total: 0.4397s High Level: 0.4027s
Total: 0.4492s High Level: 0.4118s
Total: 0.4500s High Level: 0.4131s
Total: 0.4495s High Level: 0.4123s
Total: 0.4601s High Level: 0.4227s
Total: 0.4395s High Level: 0.4038s
Total: 0.4488s High Level: 0.4108s
Total: 0.4403s High Level: 0.4046s
Total: 0.4402s High Level: 0.4042s
Total: 0.4386s High Level: 0.4024s
Total: 0.4443s High Level: 0.0001s
Total: 0.0002s High Level: 0.0001s
Total: 0.4554s High Level: 0.4222s
Total: 0.0058s High Level: 0.0033s
Total: 0.4503s High Level: 0.4143s
Total: 0.4506s High Level: 0.4141s
Total: 0.4486s High Level: 0.4118s
Total: 0.4400s High Level: 0.4039s
Total: 0.4523s High Level: 0.4189s
Total: 0.0064s High Level: 0.0033s
Total: 0.4441s High Level: 0.0001s
Total: 0.0002s High Level: 0.0002s
Total: 0.4523s High Level: 0.4150s
Total: 0.4499s High Level: 0.4133s
Total: 0.4434s High Level: 0.4111s
Total: 0.0002s High Level: 0.0002s
Total: 0.4531s High Level: 0.4165s
Total: 0.4503s High Level: 0.4121s
Total: 0.4425s High Level: 0.0000s
Total: 0.0032s High Level: 0.0008s
Total: 0.4437s High Level: 0.0001s
Total: 0.0030s High Level: 0.0009s
Total: 0.4507s High Level: 0.4140s
Total: 0.4434s High Level: 0.0001s
Total: 0.0001s High Level: 0.0000s
Total: 0.4417s High Level: 0.4058s
Total: 0.4501s High Level: 0.4129s
Total: 0.4495s High Level: 0.4138s
Total: 0.4498s High Level: 0.4130s
Total: 0.4501s High Level: 0.4136s
Total: 0.4396s High Level: 0.4034s
Total: 0.4496s High Level: 0.4128s
Total: 0.4497s High Level: 0.4136s
Total: 0.4420s High Level: 0.4084s
Total: 0.0061s High Level: 0.0034s
Total: 0.4348s High Level: 0.0001s
Total: 0.0030s High Level: 0.0006s

17楼 巨大八爪鱼 2017-4-2 15:48

【将右LED灯短路后测得的数据】
Total: 0.0087s High Level: 0.0000s
Total: 0.0001s High Level: 0.0000s
Total: 0.0008s High Level: 0.0008s
Total: 0.0001s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0681s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0681s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.6003s High Level: 0.2991s
Total: 0.0000s High Level: 0.0000s
Total: 0.1081s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0026s High Level: 0.0026s
Total: 0.0000s High Level: 0.0000s
Total: 0.0031s High Level: 0.0031s
Total: 0.0000s High Level: 0.0000s
Total: 0.0058s High Level: 0.0058s

18楼 巨大八爪鱼 2017-4-2 15:49

【将两个LED灯都短路后测得的数据】
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0024s
Total: 0.0002s High Level: 0.0004s
Total: 0.0000s High Level: 0.0000s
Total: 0.0001s High Level: 0.0003s
Total: 0.0065s High Level: 0.0065s
Total: 0.0000s High Level: 0.0011s
Total: 0.0000s High Level: 0.0000s
Total: 0.0001s High Level: 0.0001s
Total: 0.0025s High Level: 0.0025s
Total: 0.0037s High Level: 0.0037s
Total: 0.0002s High Level: 0.0002s
Total: 0.0000s High Level: 0.0004s
Total: 0.0001s High Level: 0.0000s
Total: 0.0067s High Level: 0.0067s
Total: 0.0002s High Level: 0.0004s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0002s High Level: 0.0002s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0007s
Total: 0.0066s High Level: 0.0066s
Total: 0.0002s High Level: 0.0002s
Total: 0.0000s High Level: 0.0002s
Total: 0.0001s High Level: 0.0001s
Total: 0.0004s High Level: 0.0004s
Total: 0.0000s High Level: 0.0011s
Total: 0.0000s High Level: 0.0001s
Total: 0.0000s High Level: 0.0000s
Total: 0.0068s High Level: 0.0068s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0007s
Total: 0.0064s High Level: 0.0064s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0001s High Level: 0.0001s
Total: 0.0032s High Level: 0.0032s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0002s High Level: 0.0004s
Total: 0.0067s High Level: 0.0067s
Total: 0.0002s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0002s High Level: 0.0002s
Total: 0.0056s High Level: 0.0056s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0056s High Level: 0.0017s
Total: 0.0089s High Level: 0.0089s
Total: 0.0000s High Level: 0.0008s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0064s High Level: 0.0064s
Total: 0.0002s High Level: 0.0002s
Total: 0.0000s High Level: 0.0000s
Total: 0.0001s High Level: 0.0001s
Total: 0.0001s High Level: 0.0000s
Total: 0.0002s High Level: 0.0002s
Total: 0.0000s High Level: 0.0000s
Total: 0.0002s High Level: 0.0002s
Total: 0.0065s High Level: 0.0065s
Total: 0.0001s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0001s High Level: 0.0001s
Total: 0.0001s High Level: 0.0003s
Total: 0.0000s High Level: 0.0000s
Total: 0.0002s High Level: 0.0002s
Total: 0.0066s High Level: 0.0066s
Total: 0.0002s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0060s High Level: 0.0060s
Total: 0.0002s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0066s High Level: 0.0066s
Total: 0.0002s High Level: 0.0002s
Total: 0.0048s High Level: 0.0016s
Total: 0.0017s High Level: 0.0017s
Total: 0.0080s High Level: 0.0080s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0002s High Level: 0.0002s
Total: 0.0069s High Level: 0.0069s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0072s High Level: 0.0072s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0002s
Total: 0.0002s High Level: 0.0002s
Total: 0.0055s High Level: 0.0055s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0060s High Level: 0.0060s
Total: 0.0001s High Level: 0.0001s
Total: 0.0000s High Level: 0.0000s
Total: 0.0004s High Level: 0.0004s
Total: 0.0082s High Level: 0.0082s
Total: 0.0001s High Level: 0.0003s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0002s High Level: 0.0004s
Total: 0.0000s High Level: 0.0000s
Total: 0.0002s High Level: 0.0002s
Total: 0.0077s High Level: 0.0077s
Total: 0.0002s High Level: 0.0002s
Total: 0.0000s High Level: 0.0000s
Total: 0.0000s High Level: 0.0000s
Total: 0.0067s High Level: 0.0067s
Total: 0.0000s High Level: 0.0000s

19楼 巨大八爪鱼 2017-4-2 16:47

把多谐振荡器输出的信号接到74LS193计数器的时钟信号引脚上可以看到，计数值跳变得很不规则。有时候是加1，有时却加的是2，甚至3。因此，多谐振荡器不能用来作为数字电路的时钟源。

20楼 巨大八爪鱼 2017-4-2 18:11

STM32单片机内部有斯密特触发器来过滤外部的输入，所以多谐振荡器的噪声体现不明显。然而在普通的数字74系列芯片中可没有这样的过滤器，所以都无法正常工作。

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