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最近在準(zhǔn)備八月份的全國大學(xué)生電子設(shè)計大賽,就做了幾道往年的電賽真題,其中有一題是測頻率,要求測量頻率10Hz—2MHz,誤差小于0.1%,當(dāng)時也是一臉懵,就在論壇找資料,發(fā)現(xiàn)論壇中使用的基本都是輸入捕獲方法測頻率,但是這種方法不能測高頻,最多測幾百千赫茲,達(dá)不到題目要求。經(jīng)過和小伙伴們的一天討論,最終創(chuàng)造了一種程序,它可以測量1Hz-22MHz,并且誤差小于0.1%。下面是驗證通過的程序,算是作為一種在論壇潛伏一年多對論壇的回報吧。
單片機源程序如下:
- #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); //設(shè)置NVIC中斷分組2:2位搶占優(yōu)先級,2位響應(yīng)優(yōu)先級
- uart_init(9600); //串口初始化為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); //打印數(shù)據(jù)
- count_i=0;
- count_over=0;
- TIM3->CNT=0;
- }
- }
- }
復(fù)制代碼- #include "timer.h"
- #include "led.h"
- //通用定時器3中斷初始化
- //這里時鐘選擇為APB1的2倍,而APB1為36M
- //arr:自動重裝值。
- //psc:時鐘預(yù)分頻數(shù)
- //這里使用的是定時器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中斷
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占優(yōu)先級0級
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //從優(yōu)先級3級
- 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中斷
- TIM_ETRClockMode2Config(TIM3, TIM_ExtTRGPSC_OFF, TIM_ExtTRGPolarity_NonInverted, 0);//2分頻,上升沿有效
- TIM_SetCounter(TIM3, 0); // 清零計數(shù)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); //時鐘使能
-
- TIM_TimeBaseStructure.TIM_Period = 9; //設(shè)置在下一個更新事件裝入活動的自動重裝載寄存器周期的值
- TIM_TimeBaseStructure.TIM_Prescaler =7199; //設(shè)置用來作為TIMx時鐘頻率除數(shù)的預(yù)分頻值
- TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //設(shè)置時鐘分割:TDTS = Tck_tim
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上計數(shù)模式
- TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure); //根據(jù)指定的參數(shù)初始化TIMx的時間基數(shù)單位
-
- NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn; //TIM4中斷
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占優(yōu)先級0級
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //從優(yōu)先級3級
- 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中斷
- TIM_SetCounter(TIM4, 0); // 清零計數(shù)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) //檢查TIM4更新中斷發(fā)生與否
- {
- TIM_ClearITPendingBit(TIM4, TIM_IT_Update); //注意清除標(biāo)志位
- count_i++;
- }
- }
- /***********************************************************************************************
- ************************************************************************************************/
- u32 count_over = 0;
- void TIM3_IRQHandler(void)
- {
- if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET) //檢查TIM4更新中斷發(fā)生與否
- {
- TIM_ClearITPendingBit(TIM3, TIM_IT_Update); //注意清除標(biāo)志位
- count_over++;
- }
- }
復(fù)制代碼
所有資料51hei提供下載:
雙定時器測頻率.7z
(184.48 KB, 下載次數(shù): 216)
2019-7-21 15:10 上傳
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