等精度测量法:定时器1对被测信号计数65536个周期作为闸门时间，在这个闸门时间内定时器2对标准信号进行计数。假定在这个闸门时间内标准信号的计数值为M。则有：65536/fc=M/fb通过这个公式就可以算出被测信号：fc=65536*fb/M。
6 `0 z& J3 ~* m8 O7 }8 ^6 r# H6 G本程序利用定时器3产生30KHZ的被测信号。定时器1对被测信号进行65536个周期计数。
定时器4产生60KHZ的标准信号。定时器2对标准信号在定时器1产生的闸门时间内计数。
主程序如下：
/**
  ******************************************************************************
) W$ d& I% o' y6 F" o8 p8 ^  * @file    app.c
  * @author  wangfei
  * @date    13-April-2012
  * @e-mail  wfmjj@hotmail.com
  * @brief   Initialize peripherals.
  *****************************************************************************/
/* Includes ------------------------------------------------------------------*/
#include "stm32f4xx.h"
3 I% ~+ W% J; Y, V, O: U7 a2 N#include "app.h"
. k' t3 |) T3 y/ D  o#include "bsp.h"
/* Private typedef -----------------------------------------------------------*/
, x5 W$ P0 c3 g+ T/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
2 U9 i9 @1 D6 r! \$ j/* Private variables ---------------------------------------------------------*/
! q0 C1 q7 l' `9 R" R& m6 ~8 vextern uint8_t TimeFlag;
extern uint32_t n_Counter;
uint16_t Counterh,Counterl;
0 y$ R0 l& r0 `) V& [uint8_t Data[5];
/ }9 a$ N' u% J. t4 h/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*//**
* @brief   This function handles NMI exception.
  * @param  None
  * @retval None
+ b& _; {/ T2 A  */
int main(void)
7 [) p% q! ~. [0 G# |$ s" {{
GPIO_ResetBits(GPIOE,(GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_3));  //可以通过观察LED口高电平时间
Bsp_Init();
- n: d+ v3 T9 Z& h5 u- rwhile(1)
{
   uint8_t i;
6 p/ _" f6 p6 e# ?# |5 }% }) m   TIM_ITConfig(TIM1,TIM_IT_Trigger,ENABLE);  //允许定时器1的触发中断
   GPIO_SetBits(GPIOE,(GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_3));
4 c# ^) ?; ^' }3 Z3 C7 C+ r- C9 M     TIM_Cmd(TIM1,ENABLE);                 //打开定时器1,当检测到TIM1_CH1通道的上升沿后立即触发中断
9 p* C; l. Q, Z$ Z8 Z. f/ Z    while(TimeFlag==0);     //等待定时器1溢出中断
   TIM1->DIER&=0X0000;     //失能定时器1的所有中断
1 s- _3 d: R* t, {7 G   GPIO_ResetBits(GPIOE,(GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_3));  //可以通过观察LED口高电平时间
   TimeFlag=0;    //定时器1溢出标志置0
Counterh=n_Counter>>16;  //得到32位数据中的高16位
   Counterl=n_Counter;     //得到32位数据中的低16位
" `9 J9 \2 {9 }4 V6 ]% F2 N   Data[0]=Counterh>>8;
   Data[1]=Counterh;
: b9 L. _, w2 B7 t$ V/ m   Data[2]=Counterl>>8;
# y  ^2 a. J6 V3 {% c+ Y   Data[3]=Counterl;
: j' k+ Z8 ]$ u* }, e( C* ]0 m% ]<span style="color: rgb(34, 34, 34); font-family: sans-serif; font-size: 18px; line-height: 27px; background-color: rgb(238, 238, 238); ">  for(i=0;iCCMR1|=0X0100;  //配置定时器1为外部时钟模式1
TIM1->CCER&=0XFF5F;
TIM1->SMCR|=0X0067;
TIM_ClearFlag(TIM1,(TIM_FLAG_Update|TIM_FLAG_Trigger));
}
/**
  * @brief   This function config timer3.
5 g( F* E/ {5 _- r  * @param  None
5 i# \4 p: D' q% ]/ \* T  * @retval None
3 I$ S" ^2 m) W+ E$ \/ P  */
9 K. _: x& q$ [2 i( Xvoid Bsp_TIM3_Config(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);   //Open TIM3  Clock
& n/ [* a! S3 v  p0 a; q
  {1 I  q0 D, [  E* W; L- ^  [$ {TIM_TimeBaseStructure.TIM_Prescaler=3;          //clk_cnt prescale
- o0 y+ `! W. T0 i0 [7 b3 ITIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;   //TIM3 Count mode
2 f; ?- I5 A, U$ d2 V" e$ bTIM_TimeBaseStructure.TIM_Period=699;         //Fout_clk=Fclk_cnt/(ARR+1)=21000000/700=30KHZ
# h" X4 T+ E8 I) KTIM_TimeBaseStructure.TIM_ClockDivision=0;   
: M* {8 U8 d1 B2 x1 t8 w( k
/ w+ {5 V. t: B; ~TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
. ^% t, ?! J; c/* PWM1 Mode configuration: TIM3_Ch1 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;               //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc1 as output
) J. r, z& u6 B3 aTIM_OCInitStructure.TIM_Pulse=350;                            //config TIM3_CCR1 vaule
7 E5 ]( f0 ^, lTIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //config oc1 high level avaliable
. D. |& v; z! R2 H6 {TIM_OC1Init(TIM3, &TIM_OCInitStructure);

7 A5 i2 j* I8 `' w* \" S5 d* oTIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);         // turn on oc1 preload

/* PWM1 Mode configuration: TIM3_Ch2 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;               //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc2 as output
' x5 O& x" \& _TIM_OCInitStructure.TIM_Pulse=200;                            //config TIM3_CCR2 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //config oc2 high level avaliable
7 O! W8 o1 y7 x) |! |TIM_OC2Init(TIM3, &TIM_OCInitStructure);

TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);         // turn on oc2 preload
/* PWM1 Mode configuration: TIM3_CH3 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;               //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc3 as output
TIM_OCInitStructure.TIM_Pulse=100;                            //config TIM3_CCR1 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //config oc3 high level avaliable
7 Z5 r4 p, p0 o# @* c/ lTIM_OC3Init(TIM3, &TIM_OCInitStructure);

TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);         // turn on oc3 preload

9 E& K/ F/ v4 e/* PWM1 Mode configuration: TIM3_CH4 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;               //select PWM1 mode
2 }+ @- K4 {& S! u  @% S( RTIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc4 as output
TIM_OCInitStructure.TIM_Pulse=500;                            //config TIM3_CCR1 vaule
' r& ^; y" N( y7 ~, STIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //config oc4 high level avaliable
4 ^' Q8 v4 h9 k) T1 @TIM_OC4Init(TIM3, &TIM_OCInitStructure);

TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);         // turn on oc4 preload
TIM_ARRPreloadConfig(TIM3, ENABLE);  /* TIM3 enable counter */
( V  O- k' d! W$ B  TIM_Cmd(TIM3, ENABLE);
}

/ c+ }1 ^% t1 Z

/**
# g& h$ ?, H) [* o& ~0 |" \% ^  * @brief   This function config usart3.
  * @param  None
: ^# \* A9 Q5 i8 g: L' I  * @retval None
  */
void Bsp_USART3_Config(void)
{
: K3 U$ |1 K3 t7 q2 z) p  IUSART_InitTypeDef USART_InitStructure;
$ E- b. Y( N) c" q% ^) q* U; b  
3 C6 S" b( l$ w5 {, [8 q9 `/ i  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3,ENABLE); //turn on usart3 clock
0 u2 |8 a# P9 r0 u: U  
6 @4 q- J5 z# L  USART_InitStructure.USART_BaudRate =115200 ;         //波特率设置
  USART_InitStructure.USART_WordLength = USART_WordLength_8b;
& ~: n, {5 r, Y$ X  USART_InitStructure.USART_StopBits = USART_StopBits_1;
  USART_InitStructure.USART_Parity = USART_Parity_No;
  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
% [& [6 r* @+ @  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
  USART_Init(USART3, &USART_InitStructure);
- Y7 b/ k1 ~- F  
6 |2 o1 K. a$ @3 ]  //USART_ITConfig(USART3,USART_IT_RXNE,ENABLE);
: ~$ E9 k. l, h  USART_Cmd(USART3,ENABLE);
. |  u' ]* l; {" s# E$ h  USART_ClearFlag(USART3, USART_FLAG_TC);   //清除发送完成标志位
}
  j6 P+ B! W7 X( Z0 n( s/**
+ M5 N0 n- i' |& ?/ @* A9 a  * @brief   This function config nvic.
  * @param  None
  * @retval None
& d3 Z% p' @) b; D/ J8 s  */
2 b1 x0 x, y" z7 g# evoid Bsp_NVIC_Config(void)
5 l/ ^8 z5 d6 T( B$ N{
  NVIC_InitTypeDef NVIC_InitStructure;
" b9 x$ Y% V1 n# G- x$ W$ ~) d   NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
, P3 S8 P" {* B' d# V% n: V
, j9 X; E# r. ?# ~  NVIC_InitStructure.NVIC_IRQChannel=TIM1_TRG_COM_TIM11_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
8 r! _  B8 i( t+ u/ B5 o7 A   NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
   NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
. \1 Z0 a2 ]. }; ~  B) s   NVIC_Init(&NVIC_InitStructure);
) a% n, ?- a- e: n& ]  k
  NVIC_InitStructure.NVIC_IRQChannel=TIM1_UP_TIM10_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
   NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
   NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
9 q4 E, v# X; j1 M- e8 ^   NVIC_Init(&NVIC_InitStructure);
}
/**
  * @brief   This function config timer2.
% h. `- }- I% P! I: A. [5 M, G1 w  * @param  None
: h( \: @$ [7 @8 f& I- S& A& ~  * @retval None
" |) f  z: H& m! J1 @$ v. u& v  */
void Bsp_TIM2_Config(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
; r% N+ m6 [! r+ e2 U
6 m% y& `6 o; Q; @* o) b+ t2 XRCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);  //打开定时器2的时钟
  TIM_DeInit(TIM2);

TIM_TimeBaseStructure.TIM_Prescaler=0;                       
  TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;      //定时器2向上计数
) e% u2 U* U5 O) C! s5 `) S  TIM_TimeBaseStructure.TIM_Period=0xffff;                        
  U6 c& P2 z$ t  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

8 s* A: B2 M: f1 Y( ]TIM2->ARR|=0XFFFFFFFF;   //配置
- G* O# {- s% N1 H6 L" m//定时器2外部时钟模式1的配置
; [7 O: ^! }0 I3 ]% Q" O6 xTIM2->CCMR1|=0X0001;   
5 i; c% k1 o  STIM2->CCER&=0XFFF5;
% s9 F' j# N) r/ |8 }3 wTIM2->SMCR|=0X0057;
" x- v7 M$ }2 ?. S  A
TIM_ClearFlag(TIM2,TIM_FLAG_Update);    //初始化时必须将溢出中断清0必须在开溢出中断之前。
}
: i; f& I8 Y. m1 H/**
) M9 ~5 t; ]9 K* M  * @brief   This function config timer4.
$ ]0 G. Q: n( n4 y* y2 p  * @param  None
  * @retval None
0 ~& g1 Z: `, O& R- g* B9 j0 ~  */
3 j$ M& b4 N, e, |; x- Qvoid Bsp_TIM4_Config(void)
8 a! o6 t+ A  ^, O- s5 \, \{
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
% l' n! N; G& W7 [& _% c) aTIM_OCInitTypeDef TIM_OCInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4,ENABLE);  //turn on TIM4 clock TIM_TimeBaseStructure.TIM_Prescaler=1;          //Fck_cnt=84MHZ/2=42MHZ
$ x6 [; e: P& t/ m8 n* ZTIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;   //TIM3 Count mode
TIM_TimeBaseStructure.TIM_Period=699;         //Fout_clk=Fclk_cnt/(ARR+1)=42000/700=60KHZ
TIM_TimeBaseStructure.TIM_ClockDivision=0;   

2 B/ g/ S8 m! Z% s1 hTIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);
7 `! m9 V' w2 C- l. |. B* K4 o+ X5 g$ b
/* PWM1 Mode configuration: TIM4_Ch1 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;               //select PWM1 mode
- Q# m, P7 H$ oTIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc1 as output
$ d1 e4 V6 _* ~7 ATIM_OCInitStructure.TIM_Pulse=350;                            //config TIM3_CCR1 vaule
+ H9 J' o0 x# L8 T6 vTIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //config oc1 high level avaliable
: Z9 I6 Y8 U) A: N! MTIM_OC1Init(TIM4, &TIM_OCInitStructure);

TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable);         // turn on oc1 preload

/* PWM1 Mode configuration: TIM4_Ch2 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;               //select PWM1 mode
) s: H, W7 k6 d! K' W6 uTIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc2 as output
TIM_OCInitStructure.TIM_Pulse=500;                            //config TIM3_CCR2 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //config oc2 high level avaliable
; a* u+ X) \0 q; VTIM_OC2Init(TIM4, &TIM_OCInitStructure);
. |; s) l+ Q  z) p! X
5 \# ?' l6 x; b- A# _/ mTIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable);         // turn on oc2 preload
& t1 e1 ^# h" C/ ]
: t( I  A, Y+ N9 B- g" h4 X/* PWM1 Mode configuration: TIM4_CH3 */
- I' V& Z- r! I* m5 ~& S' DTIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;               //select PWM1 mode
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc3 as output
TIM_OCInitStructure.TIM_Pulse=100;                            //config TIM3_CCR1 vaule
) L( p  s. t, s$ z* pTIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //config oc3 high level avaliable
1 i$ w/ E: S, c9 R" w5 ITIM_OC3Init(TIM4, &TIM_OCInitStructure);
, ~+ _( [- N! [5 W! F8 v) {
TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Enable);         // turn on oc3 preload
/* PWM1 Mode configuration: TIM4_CH4 */
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;               //select PWM1 mode
  I; \# `! ?- u: W2 BTIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //config oc4 as output
$ Q" M/ l. P! Y% y( a0 f5 ]+ }TIM_OCInitStructure.TIM_Pulse=600;                            //config TIM3_CCR1 vaule
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //config oc4 high level avaliable
# {& \: C7 B3 Z  \TIM_OC4Init(TIM4, &TIM_OCInitStructure);
+ g' m2 V1 |, Z9 B: m2 Q
TIM_OC4PreloadConfig(TIM4, TIM_OCPreload_Enable);         // turn on oc4 preload
: p1 U6 `0 ~/ g
TIM_ARRPreloadConfig(TIM4, ENABLE);  /* TIM3 enable counter */
  TIM_Cmd(TIM4, ENABLE);

}
$ e* S9 y% i2 s- J( ?: P6 S定时器1触发中断程序如下：
* o' x( y6 [8 M2 n! \void TIM1_TRG_COM_TIM11_IRQHandler(void)
{
if(TIM_GetITStatus(TIM1,TIM_IT_Trigger)==SET)  //检查是否为触发中断
{
  TIM1->DIER&=0XFFBF;    //清除定时器1的触发中断
  TIM1->DIER|=0X0001;    //使能定时器1的溢出中断
  TIM2->CR1|=0X0001;    //打开定时器2使其对标准信号开始计数
  TIM1->SR&=0XFFBF;     //在退出中断之前必须清除其中断标志位
! n. Y/ F2 U  ]}
}
定时器1溢出中断如下：
void TIM1_UP_TIM10_IRQHandler(void)
! b, D; g) T1 V4 @; z& ]{
/ a, o) F: T5 R4 d* r  N# uif(TIM_GetITStatus(TIM1,TIM_IT_Update)==SET)  //检查定时器1溢出标志位是否置1
4 S& j6 C, z$ T* T) Z{
  n_Counter=TIM2->CNT;  //读出计数器2的值
1 K) t% h. @0 D7 j1 \1 s  TIM1->CR1&=0XFFFE;    //关闭定时器1
  TIM2->CR1&=0XFFFE;    //关闭定时器2
3 o+ ?6 \- x6 |) A! l9 M2 {1 A  TIM2->CNT&=0X0000;    //清除计数器2计数寄存器的值
  TimeFlag=1;          //1s标志位置1
  TIM1->SR&=0XFFFE;    //退出定时器1溢出中断之前,必须清除定时器1的溢出标志位
: S0 y. b1 `" ^' G* j2 a}
}
/ [1 F. i8 o$ X' F" ^0 Q$ ]9 P+ ~</i>
! P/ y, S, G8 }

被测信号 标准信号和串口输出如下图！
2 v' g1 k% c' {5 J. c  `* M2 E7 @
* T6 Y* Y7 C+ B; w

收藏下，以后再用。

收藏下，谢谢

收藏下，谢谢