Null Pointer Exception with Arduino Communication

Processing Electronics (Arduino, etc.)
19

Ok so I finally got them to communicate and decompose the string correctly! Instead of using the string class, I just made a “char” array of whatever I wanted, and utilized what jafal sent to me (its in another tab). I am now running into the problem of the motors not running now, but that could be a power issue at this point. Heres what I got.

Arduino:

#include <Wire.h>
#include <Servo.h>
#include <Adafruit_MotorShield.h>

//set up motorhsield
Adafruit_MotorShield AFMS = Adafruit_MotorShield(0x60);

//assign motors
Adafruit_DCMotor *RailMotor = AFMS.getMotor(1);
Adafruit_DCMotor *Swivel = AFMS.getMotor(2);
Adafruit_DCMotor *Elbow = AFMS.getMotor(3);
Adafruit_DCMotor *Screw = AFMS.getMotor(4);

//call the servo library
Servo DrillArm;
Servo ClawArm;
Servo Claw;

const byte number_of_chars = 32;
char receivedChars[number_of_chars];
boolean new_data = false;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(LED_BUILTIN, OUTPUT);
  // create with the default frequency 1.6KHz
  AFMS.begin();

  // Attach a servo to pin #10 and pin #9
  DrillArm.attach(11);
  ClawArm.attach(10);
  Claw.attach(9);

  // turn on motor M1
  RailMotor->setSpeed(300);
  RailMotor->run(FORWARD);
  RailMotor->run(BACKWARD);
  RailMotor->run(RELEASE);

  // turn on M2
  Swivel->setSpeed(200);
  Swivel->run(FORWARD);
  Swivel->run(BACKWARD);
  Swivel->run(RELEASE);

  // turn on motor M3
  Elbow->setSpeed(200);
  Elbow->run(FORWARD);
  Elbow->run(BACKWARD);
  Elbow->run(RELEASE);

  // turn on M4
  Screw->setSpeed(200);
  Screw->run(FORWARD);
  Screw->run(BACKWARD);
  Screw->run(RELEASE);
}

//setting variables

void loop() {
  // put your main code here, to run repeatedly:

  receivePacket();
  if (new_data == true) {
    parseData();
    executeParsedData();
    new_data = false;
    Serial.println(receivedChars);
    char buf[4] = {receivedChars[1], receivedChars[2], receivedChars[3], receivedChars[4]};
    int mapp = atoi(buf);
    Serial.println(mapp);

    if (receivedChars[0] == 'A'){ //claw arm control
      Serial.println(receivedChars);
      ClawArm.write(map(mapp, 0, 180, 0, 180));
    }

    if (receivedChars[0] == 'B'){ //elbow control
      Serial.println(receivedChars);
      Elbow->setSpeed(mapp);
      Elbow->run(FORWARD);
      delay(2000);
    }
    
    if (receivedChars[0] == 'C'){ //claw open/close
      Serial.println(receivedChars);
      Claw.write(map(mapp, 0, 180, 0, 180));
    }

    if (receivedChars[0] == 'D'){ //drill arm control
      Serial.println(receivedChars);
      DrillArm.write(map(mapp, 0, 180, 0, 180));
    }

    if (receivedChars[0] == 'E'){ //rail control
      Serial.println(receivedChars);
      RailMotor->setSpeed(mapp);
      RailMotor->run(FORWARD);
      delay(2000);
    }

    if (receivedChars[0] == 'F'){ //swivel control
      Serial.println(receivedChars);
      Swivel->setSpeed(mapp);
      Swivel->run(FORWARD);
      delay(2000);
    }
    
    if (receivedChars[0] == 'G'){ //screw control
      Serial.println(receivedChars);
      Screw->setSpeed(mapp);
      Screw->run(FORWARD);
      delay(2000);
    }
    
  }
  
}

Processing:

import processing.serial.*;
import net.java.games.input.*;
import org.gamecontrolplus.*;
import org.gamecontrolplus.gui.*;

Serial port;
ControlDevice cont;
ControlIO control;
Arduino arduino;
float swivel, screw, rail, selectcontrol;
boolean shoulderselect, elbowselect, clawarmselect, clawgrab, clawrelease;
String portmessage;

PImage splash;

void setup(){
  size(700, 400);
  control = ControlIO.getInstance(this);
  cont = control.getMatchedDevice("STAR_2021_Artificial_Astronauts_controls");
  
  if (cont == null) {
    println("No suitable device configured, exiting program"); 
    System.exit(-1);
  }
  
  splash = loadImage("Artificial Astronaut Control Scheme");
  println((Object[])Serial.list());
  port = new Serial(this, "COM8", 9600);
}

public void getUserInput() {
  screw = map(cont.getSlider("Screw").getValue(), -1, 1, 0, 180);
  swivel = map(cont.getSlider("SwivelJoint").getValue(), -1, 1, 0, 180);
  rail = map(cont.getSlider("Rail").getValue(), -1, 1, 0, 180);
  selectcontrol = map(cont.getSlider("SelectControl").getValue(), -1, 1, 0, 360);
  shoulderselect = cont.getButton("ShoulderSelect").pressed();
  elbowselect = cont.getButton("ElbowSelect").pressed();
  clawarmselect = cont.getButton("ClawArmSelect").pressed();
  clawgrab = cont.getButton("ClawGrab").pressed();
  clawrelease = cont.getButton("ClawRelease").pressed();
}


            
void draw() {
  getUserInput();
  background(selectcontrol,400,400);
  println("You are now in Control >:)");
  //send a list that consists of the joint's name and, position(and direction) to the serial for the arduino
  
  if(clawarmselect){ //control claw arm with right stick
    println("Selecting the claw arm to control, use the right stick to control");
    portmessage = "<A"+str((int)selectcontrol)+">";
    port.write(portmessage);
  }
  
  if(elbowselect){ //control elbow with button and control right stick
    println("Selecting the elbow to control, use the right stick to control");
    portmessage = "<B"+str((int)selectcontrol)+">";
    port.write(portmessage);
  }
  
  if(clawgrab){ //close claw
    println("Claw Closing");
    port.write("<"+"C90"+">");
  }
  
  if(clawrelease){ //open claw\
    println("Claw Opening");
    port.write("<"+"C180"+">");
  }
  
  if(shoulderselect){ //control elbow with button and control right stick
    println("Selecting the shoulder to control, use the right stick to control");
    portmessage = "<D"+str((int)selectcontrol)+">";
    port.write(portmessage);
  }
  
  if(rail > 0){ //control elbow with button and control right stick
    println("Selecting the rail to control, use the left stick to control");
    portmessage = "<E"+str((int)selectcontrol)+">";
    port.write(portmessage);
  }
  
  if(swivel > 0){ //control swivel with button and control right stick
    println("Selecting the swivel to control, use the left stick to control");
    portmessage = "<F"+str((int)selectcontrol)+">";
    port.write(portmessage);
  }
  
  if(screw > 0){ //control screw with trigger buttons
    println("Selecting the elbow to control, use the right stick to control");
    portmessage = "<G"+str((int)selectcontrol)+">";
    port.write(portmessage);
  }
}