本次选用的编码器电机为13线的霍尔编码器电机，电机减速比为30：1，转动一圈输出13*30=390个脉冲。轮胎直径为75mm，轮胎周长为pi*d=3*75=225mm.定时器采用四倍频计数，则一圈输出390*4=1560个脉冲。具体编码器知识这里就不多说了。
根据测速原理：假设编码器输出的脉冲数为N，而电机转动一圈输出1569个脉冲，转动一圈轮子将前进225mm。那输出脉冲数为N时前进的距离就应该为225*（N/1560）mm，再除以时间及可得速度。
下面为具体代码：
encoder.c文件
#include "encoder.h"void Encoder_TIM2_Init(void){RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);//开时钟RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);GPIO_InitTypeDef GPIO_InitStruct;//配置IO口GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN_FLOATING;GPIO_InitStruct.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;GPIO_Init(GPIOA, &GPIO_InitStruct);TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;//定时器初始化TIM_TimeBaseInitStruct.TIM_ClockDivision = TIM_CKD_DIV1;TIM_TimeBaseInitStruct.TIM_CounterMode = TIM_CounterMode_Up;TIM_TimeBaseInitStruct.TIM_Period = 65535;TIM_TimeBaseInitStruct.TIM_Prescaler = 0;TIM_TimeBaseInit(TIM2, &TIM_TimeBaseInitStruct);//定时器编码器模式初始化TIM_EncoderInterfaceConfig(TIM2, TIM_EncoderMode_TI12, TIM_ICPolarity_Rising, TIM_ICPolarity_Rising);TIM_ICInitTypeDef TIM_ICInitStruct; //输入捕获单元配置TIM_ICStructInit(&TIM_ICInitStruct);TIM_ICInitStruct.TIM_ICFilter = 10;TIM_ICInit(TIM2, &TIM_ICInitStruct);TIM_ClearFlag(TIM2, TIM_FLAG_Update);TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);TIM_SetCounter(TIM2, 0);TIM_Cmd(TIM2, ENABLE);}void Encoder_TIM4_Init(void){RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);GPIO_InitTypeDef GPIO_InitStruct;GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN_FLOATING;GPIO_InitStruct.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;GPIO_Init(GPIOB, &GPIO_InitStruct);TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;TIM_TimeBaseInitStruct.TIM_ClockDivision = TIM_CKD_DIV1;TIM_TimeBaseInitStruct.TIM_CounterMode = TIM_CounterMode_Up;TIM_TimeBaseInitStruct.TIM_Period = 65535;TIM_TimeBaseInitStruct.TIM_Prescaler = 0;TIM_TimeBaseInit(TIM4, &TIM_TimeBaseInitStruct);TIM_EncoderInterfaceConfig(TIM4, TIM_EncoderMode_TI12, TIM_ICPolarity_Rising, TIM_ICPolarity_Rising);TIM_ICInitTypeDef TIM_ICInitStruct; TIM_ICStructInit(&TIM_ICInitStruct);TIM_ICInitStruct.TIM_ICFilter = 10;TIM_ICInit(TIM4, &TIM_ICInitStruct);TIM_ClearFlag(TIM4, TIM_FLAG_Update);TIM_ITConfig(TIM4, TIM_IT_Update, ENABLE);TIM_SetCounter(TIM4, 0);TIM_Cmd(TIM4, ENABLE);}int Read_Spead(int TIMx)//读取编码器输出脉冲数{int value_1;switch(TIMx){case 2:value_1 = (short)TIM_GetCounter(TIM2);TIM_SetCounter(TIM2, 0);break;case 4:value_1 = (short)TIM_GetCounter(TIM4);TIM_SetCounter(TIM4, 0);break;default:value_1 = 0;}return value_1;}void TIM2_IRQHander(void){if(TIM_GetITStatus(TIM2, TIM_IT_Update) == 1){TIM_ClearITPendingBit(TIM2, TIM_IT_Update);}}void TIM4_IRQHander(void){if(TIM_GetITStatus(TIM4, TIM_IT_Update) == 1){TIM_ClearITPendingBit(TIM4, TIM_IT_Update);}}
我使用的是简单的delay一下来采集定时器捕获的编码器脉冲数，不过我建议使用定时器中断来处理编码器采集。此函数只采集右轮脉冲进行计算
主函数循环体内函数：
while(1){delay_s(1);{uint16_t right = Read_Spead(2);//采集右轮脉冲数displacement = 0.225 * (right / 1560);//计算位移speed = displacement;//由于我设置的为延时一秒就不用除时间OLED_Float(0, 0, speed, 4);//通过OLED显示速度set_PWM(999);//设置电机PWMTIM_SetCounter(TIM2, 0);//下一次一秒计数前再一次将计数清零}}
