第 8 章机器人底盘Arduino端编码器驱动(自学二刷笔记)

重要参考：

课程链接:https://www.bilibili.com/video/BV1Ci4y1L7ZZ

讲义链接:Introduction · Autolabor-ROS机器人入门课程《ROS理论与实践》零基础教程

8.4.3 底盘实现_02Arduino端编码器驱动

测速是整个PID闭环控制中的必须环节，我们必须修改代码适配当前AB相编码器，虽然需要重写功能，但是测速部分内容已经封装，只需要实现编码器计数即可，大致实现流程如下：

ROSArduinoBridge.ino 中需要注释之前的编码器驱动，添加自定义编码器驱动；
encoder_driver.h 中设置编码器引脚并声明初始化函数以及中断函数；
encoder_driver.ino 中实现编码器计数以及重置函数；
ROSArduinoBridge.ino 中 setup 函数调用编码器初始化函数。
测试

1.定义编码器驱动

ROSArduinoBridge.ino需要添加编码器宏定义，代码如下：

#define USE_BASE      // Enable the base controller code
//#undef USE_BASE     // Disable the base controller code/* Define the motor controller and encoder library you are using */
#ifdef USE_BASE/* The Pololu VNH5019 dual motor driver shield *///#define POLOLU_VNH5019/* The Pololu MC33926 dual motor driver shield *///#define POLOLU_MC33926/* The RoboGaia encoder shield *///#define ROBOGAIA/* Encoders directly attached to Arduino board *///#define ARDUINO_ENC_COUNTER#define ARDUINO_MY_COUNTER/* L298 Motor driver*///#define L298_MOTOR_DRIVER#define L298P_MOTOR_DRIVER
#endif

先去除 #define L298P_MOTOR_DRIVER 的注释，否则后续编译会抛出异常。

2.修改encoder_driver.h文件

修改后内容如下：

/* *************************************************************Encoder driver function definitions - by James Nugen************************************************************ */#ifdef ARDUINO_ENC_COUNTER//below can be changed, but should be PORTD pins; //otherwise additional changes in the code are required#define LEFT_ENC_PIN_A PD2  //pin 2#define LEFT_ENC_PIN_B PD3  //pin 3//below can be changed, but should be PORTC pins#define RIGHT_ENC_PIN_A PC4  //pin A4#define RIGHT_ENC_PIN_B PC5   //pin A5
#elif defined ARDUINO_MY_COUNTER#define LEFT_A 21#define LEFT_B 20#define RIGHT_A 18#define RIGHT_B 19void initEncoders();void leftEncoderEventA();void leftEncoderEventB();void rightEncoderEventA();void rightEncoderEventB();
#endiflong readEncoder(int i);
void resetEncoder(int i);
void resetEncoders();

3.修改encoder_driver.ino 文件

主要添加内容如下：

#elif defined ARDUINO_MY_COUNTERvolatile long left_count = 0L;volatile long right_count = 0L;void initEncoders(){pinMode(LEFT_A,INPUT); // 21  --- 2pinMode(LEFT_B,INPUT); // 20  --- 3pinMode(RIGHT_A,INPUT);// 18  --- 5pinMode(RIGHT_B,INPUT);// 19  --- 4attachInterrupt(2,leftEncoderEventA,CHANGE);attachInterrupt(3,leftEncoderEventB,CHANGE);attachInterrupt(5,rightEncoderEventA,CHANGE);attachInterrupt(4,rightEncoderEventB,CHANGE);}void leftEncoderEventA(){if(digitalRead(LEFT_A) == HIGH){if(digitalRead(LEFT_B) == HIGH){left_count++;} else {left_count--;}} else {if(digitalRead(LEFT_B) == LOW){left_count++;} else {left_count--;}}}void leftEncoderEventB(){if(digitalRead(LEFT_B) == HIGH){if(digitalRead(LEFT_A) == LOW){left_count++;} else {left_count--;}} else {if(digitalRead(LEFT_A) == HIGH){left_count++;} else {left_count--;}}}void rightEncoderEventA(){if(digitalRead(RIGHT_A) == HIGH){if(digitalRead(RIGHT_B) == HIGH){right_count++;} else {right_count--;}} else {if(digitalRead(RIGHT_B) == LOW){right_count++;} else {right_count--;}}  }void rightEncoderEventB(){if(digitalRead(RIGHT_B) == HIGH){if(digitalRead(RIGHT_A) == LOW){right_count++;} else {right_count--;}} else {if(digitalRead(RIGHT_A) == HIGH){right_count++;} else {right_count--;}}  }long readEncoder(int i) {if (i == LEFT) return left_count;else return right_count;}/* Wrap the encoder reset function */void resetEncoder(int i) {if (i == LEFT){left_count=0L;return;} else { right_count=0L;return;}}

4.ROSArduinoBridge.ino 实现初始化

setup 添加语句：initEncoders()；

void setup() {Serial.begin(BAUDRATE);// Initialize the motor controller if used */
#ifdef USE_BASE#ifdef ARDUINO_ENC_COUNTER//set as inputsDDRD &= ~(1<<LEFT_ENC_PIN_A);DDRD &= ~(1<<LEFT_ENC_PIN_B);DDRC &= ~(1<<RIGHT_ENC_PIN_A);DDRC &= ~(1<<RIGHT_ENC_PIN_B);//enable pull up resistorsPORTD |= (1<<LEFT_ENC_PIN_A);PORTD |= (1<<LEFT_ENC_PIN_B);PORTC |= (1<<RIGHT_ENC_PIN_A);PORTC |= (1<<RIGHT_ENC_PIN_B);// tell pin change mask to listen to left encoder pinsPCMSK2 |= (1 << LEFT_ENC_PIN_A)|(1 << LEFT_ENC_PIN_B);// tell pin change mask to listen to right encoder pinsPCMSK1 |= (1 << RIGHT_ENC_PIN_A)|(1 << RIGHT_ENC_PIN_B);// enable PCINT1 and PCINT2 interrupt in the general interrupt maskPCICR |= (1 << PCIE1) | (1 << PCIE2);#elif defined ARDUINO_MY_COUNTERinitEncoders();#endifinitMotorController();resetPID();
#endif/* Attach servos if used */#ifdef USE_SERVOSint i;for (i = 0; i < N_SERVOS; i++) {servos[i].initServo(servoPins[i],stepDelay[i],servoInitPosition[i]);}#endif}