原创 stm32学习——两轮平衡小车之定时器正交编码器功能应用

废话不说，先上代码

#include "main.h"

/*

PA7——TIM3_CH2

PA6——TIM3_CH1

PB7——TIM4_CH2

PB6——TIM4_CH1

*/

int Timer3_Overflow;

int Timer4_Overflow;

void wheel_encoder_configuration(void)

{

         GPIO_InitTypeDef                                        ENCODER;

         TIM_TimeBaseInitTypeDef    TIMER3,  TIMER4;

         TIM_ICInitTypeDef                                      IC_ENCODER;

         NVIC_InitTypeDef                                        nvic;

         RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA|RCC_AHB1Periph_GPIOB, ENABLE);

         RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3|RCC_APB1Periph_TIM4, ENABLE);

         //PA6、PA7的复用功能一定要分开配置才行

         GPIO_PinAFConfig(GPIOA,GPIO_PinSource6, GPIO_AF_TIM3);

         GPIO_PinAFConfig(GPIOA,GPIO_PinSource7, GPIO_AF_TIM3);

         ENCODER.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;

         ENCODER.GPIO_Mode = GPIO_Mode_AF;

         ENCODER.GPIO_Speed = GPIO_Speed_100MHz;

         ENCODER.GPIO_PuPd = GPIO_PuPd_DOWN;

         GPIO_Init(GPIOA, &ENCODER);

         GPIO_PinAFConfig(GPIOB,GPIO_PinSource6, GPIO_AF_TIM4);

         GPIO_PinAFConfig(GPIOB,GPIO_PinSource7, GPIO_AF_TIM4);

         ENCODER.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;

         ENCODER.GPIO_Mode = GPIO_Mode_AF;

         ENCODER.GPIO_Speed = GPIO_Speed_100MHz;

         ENCODER.GPIO_PuPd = GPIO_PuPd_DOWN;

         GPIO_Init(GPIOB, &ENCODER);

         /***********configure the TIM3**********/

         TIMER3.TIM_Prescaler = 0;

         TIMER3.TIM_Period = 0xffff;

         TIMER3.TIM_ClockDivision = TIM_CKD_DIV1;

         TIMER3.TIM_CounterMode = TIM_CounterMode_Up;  

         TIM_TimeBaseInit(TIM3, &TIMER3);

         /***********configure the TIM4***********/

         TIMER4.TIM_Prescaler = 0;

         TIMER4.TIM_Period = 0xffff;

         TIMER4.TIM_ClockDivision = TIM_CKD_DIV1;

         TIMER4.TIM_CounterMode = TIM_CounterMode_Up;  

         TIM_TimeBaseInit(TIM4, &TIMER4);

         /**********Set TIM3 and TIM4 to the ecoder mode***************/

         TIM_EncoderInterfaceConfig(TIM3, TIM_EncoderMode_TI12, TIM_ICPolarity_Falling, TIM_ICPolarity_Falling);

         TIM_EncoderInterfaceConfig(TIM4, TIM_EncoderMode_TI12, TIM_ICPolarity_Falling, TIM_ICPolarity_Falling);

         /**********Set TIM3 and TIM4 to the input capture mode***************/

         IC_ENCODER.TIM_Channel    =       TIM_Channel_1;

         IC_ENCODER.TIM_ICSelection        =       TIM_ICSelection_DirectTI;

         TIM_ICInit(TIM3, &IC_ENCODER);

         IC_ENCODER.TIM_Channel    =       TIM_Channel_2;

         IC_ENCODER.TIM_ICSelection        =       TIM_ICSelection_DirectTI;

         TIM_ICInit(TIM3, &IC_ENCODER);

         IC_ENCODER.TIM_Channel    =       TIM_Channel_1;

         IC_ENCODER.TIM_ICSelection        =       TIM_ICSelection_DirectTI;

         TIM_ICInit(TIM4, &IC_ENCODER);

         IC_ENCODER.TIM_Channel    =       TIM_Channel_2;

         IC_ENCODER.TIM_ICSelection        =       TIM_ICSelection_DirectTI;

         TIM_ICInit(TIM4, &IC_ENCODER);

         /*************Configurate interrupts of TIM3 and TIM4*********/

         nvic.NVIC_IRQChannel = TIM3_IRQn;

         nvic.NVIC_IRQChannelPreemptionPriority = 2;

         nvic.NVIC_IRQChannelSubPriority = 2;

         nvic.NVIC_IRQChannelCmd = ENABLE;

         NVIC_Init(&nvic);

         nvic.NVIC_IRQChannel = TIM4_IRQn;

         nvic.NVIC_IRQChannelPreemptionPriority = 2;

         nvic.NVIC_IRQChannelSubPriority = 2;

         nvic.NVIC_IRQChannelCmd = ENABLE;

         NVIC_Init(&nvic);

         /*Clear the interruput flag and then enable the interrupt*/

         TIM_ClearFlag(TIM3, TIM_FLAG_Update);

         TIM_ClearFlag(TIM4, TIM_FLAG_Update);

         TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE);

         TIM_ITConfig(TIM4, TIM_IT_Update, ENABLE);

         /*Set TIM3 and TIM4 CNT to 0x7fff*/

         TIM_SetCounter(TIM3,0x7fff);

         TIM_SetCounter(TIM4,0x7fff);

         /*Enable TIM3 and TIM4 */

         TIM_Cmd(TIM3, ENABLE);

         TIM_Cmd(TIM4, ENABLE);

}

int encoderR_get_cnt(void)

{

         /*get the speed of right wheel */

         int cnt = 0;

         cnt = (TIM3 -> CNT) - 0x7fff;

         TIM3 -> CNT = 0x7fff;

         return cnt;

}

int encoderL_get_cnt(void)

{

         /*get the speed of left wheel*/

         int cnt = 0;

         cnt = (TIM4 -> CNT) - 0x7fff;

         TIM4 -> CNT = 0x7fff;

         return cnt;

}

void TIM3_IRQHandler(void)

{

         TIM_ClearFlag(TIM3, TIM_FLAG_Update);

         if(Timer3_Overflow != 0xffffffff)

         {

                   Timer3_Overflow++;

         }

}

void TIM4_IRQHandler(void)

{

         TIM_ClearFlag(TIM4, TIM_FLAG_Update);

         if(Timer4_Overflow != 0xffffffff)

         {

                   Timer4_Overflow++;

         }

}

刚开始在调试的时候遇到了问题，读出来的cnt值只有0,1，-1，而且根本没有什么规律，后来发现是gpio的配置有问题，相应的GPIO口应该配制成GPIO_Mode_AF，而不是GPIO_Mode_IN，而且配置复用功能的时候，GPIO_PinAFConfig（）函数的参数一定要注意，GPIO_PinSource参数只能写一个，不要讲多个GPIO_PinSource与在一起。比如，要配置PA6和PA7，应写成这样：

GPIO_PinAFConfig(GPIOA,GPIO_PinSource6, GPIO_AF_TIM3);

         GPIO_PinAFConfig(GPIOA,GPIO_PinSource7, GPIO_AF_TIM3);

而不要写出这样：

GPIO_PinAFConfig(GPIOA,GPIO_PinSource6| GPIO_PinSource7,  GPIO_AF_TIM3);

         程序中CNT寄存器的初值设置为0X7fff，这样的话无论一开始轮子是正转还是反转，都基本不会溢出，但是为了防止溢出的情况，又在两个定时器的中断函数中对溢出次数进行计数，在后续的应用中就可以结合溢出次数和CNT计数器的值，得到实际的计数值。