最近在准备八月份的全国大学生电子设计大赛，就做了几道往年的电赛真题，其中有一题是测频率，要求测量频率10Hz—2MHz,误差小于0.1%，当时也是一脸懵，就在论坛找资料，发现论坛中使用的基本都是输入捕获方法测频率，但是这种方法不能测高频，最多测几百千赫兹，达不到题目要求。经过和小伙伴们的一天讨论，最终创造了一种程序，它可以测量1Hz-22MHz,并且误差小于0.1%。下面是验证通过的程序，算是作为一种在论坛潜伏一年多对论坛的回报吧。
单片机源程序如下:
- #include "led.h"
- #include "delay.h"
- #include "key.h"
- #include "sys.h"
- #include "usart.h"
- #include "timer.h"
- u32 count_s;
- u32 count_ms;
- extern u32 count_i;
- extern u32 count_over;
- int main(void)
- {
- NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //设置NVIC中断分组2:2位抢占优先级，2位响应优先级
- uart_init(9600); //串口初始化为9600
- TIM3_External_Clock_CountingMode();
- TIM4_timer_Init();
- while(1)
- {
- if(count_i>1000)
- {
- count_ms = TIM3->CNT;
- count_s = count_over*65536 + count_ms;
- printf("%d \r\n ",count_s); //打印数据
- count_i=0;
- count_over=0;
- TIM3->CNT=0;
- }
- }
- }
- #include "timer.h"
- #include "led.h"
- //通用定时器3中断初始化
- //这里时钟选择为APB1的2倍，而APB1为36M
- //arr：自动重装值。
- //psc：时钟预分频数
- //这里使用的是定时器3!
- void TIM3_External_Clock_CountingMode(void)
- {
- GPIO_InitTypeDef GPIO_InitStructure;
- TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
- NVIC_InitTypeDef NVIC_InitStructure;
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE);
-
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
- GPIO_Init(GPIOD, &GPIO_InitStructure);
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
- TIM_DeInit(TIM3);
- TIM_TimeBaseStructure.TIM_Period = 0xFFFF;
- TIM_TimeBaseStructure.TIM_Prescaler = 0;
- TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
- TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
- NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //TIM4中断
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占优先级0级
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //从优先级3级
- NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
- NVIC_Init(&NVIC_InitStructure); //初始化NVIC寄存器
- TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE ); //使能指定的TIM4中断
- TIM_ETRClockMode2Config(TIM3, TIM_ExtTRGPSC_OFF, TIM_ExtTRGPolarity_NonInverted, 0);//2分频，上升沿有效
- TIM_SetCounter(TIM3, 0); // 清零计数器CNT
- TIM_Cmd(TIM3,ENABLE);
-
- }
- /***********************************************************************************************
- ************************************************************************************************/
- void TIM4_timer_Init(void)
- {
- TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
- NVIC_InitTypeDef NVIC_InitStructure;
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); //时钟使能
-
- TIM_TimeBaseStructure.TIM_Period = 9; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值
- TIM_TimeBaseStructure.TIM_Prescaler =7199; //设置用来作为TIMx时钟频率除数的预分频值
- TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //设置时钟分割:TDTS = Tck_tim
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式
- TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure); //根据指定的参数初始化TIMx的时间基数单位
-
- NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn; //TIM4中断
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占优先级0级
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //从优先级3级
- NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
- NVIC_Init(&NVIC_InitStructure); //初始化NVIC寄存器
- TIM_ITConfig(TIM4,TIM_IT_Update,ENABLE ); //使能指定的TIM4中断
- TIM_SetCounter(TIM4, 0); // 清零计数器CNT
- TIM_Cmd(TIM4, ENABLE); //使能TIM4
- }
- /***********************************************************************************************
- ************************************************************************************************/
- u32 count_i = 0;
- void TIM4_IRQHandler(void)
- {
- if (TIM_GetITStatus(TIM4, TIM_IT_Update) != RESET) //检查TIM4更新中断发生与否
- {
- TIM_ClearITPendingBit(TIM4, TIM_IT_Update); //注意清除标志位
- count_i++;
- }
- }
- /***********************************************************************************************
- ************************************************************************************************/
- u32 count_over = 0;
- void TIM3_IRQHandler(void)
- {
- if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET) //检查TIM4更新中断发生与否
- {
- TIM_ClearITPendingBit(TIM3, TIM_IT_Update); //注意清除标志位
- count_over++;
- }
- }
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双定时器测频率.7z
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