Thursday, March 8, 2012

Arduino Controlled RC Car: Update

Moving towards my goal of a WiFi controlled and camera feedback RC car, I have successfully controlled the car over Bluetooth with the "arrow keys". This is basically how it went:
A processing app reads the arrow keys and connects to the arduino bluetooth module using the internal computer Bluetooth. I put in a little parsing code for the serial output too: <1,0,0,0> the "<" and ">" represent the beginning and end of the datastream being sent. Boolean on/off logic is being used to determine which button is pressed. Think of it as; <fwd state, rev state, right state, left state> I also put in some safety checks so that forward and backward buttons can't both be on at once. The arduino the reads that data, splits it into individual values for forward, back, right, and left. Then I created a quick function that takes the split values and sets the buttons on the car remote to them(they are 0 or 1, low or high). So, then the remote sends the commands to the car and off it goes.

My final goal is to use a smartphone on the car that sends a live video feed back to the computer, and sends commands received over WiFi from the computer to the Arduino (the bluetooth sends the commands to the Arduino from the phone).

This code doesn't have to be used with Bluetooth; just connect your Arduino and tell processing to send the data to the Arduino serial port.

Pics:





Processing Code

import processing.serial.*;

Serial myPort;  // Create object from Serial class
int[] KeyArray = new int[4];
int PrtChose = 6; //number of the serial port, starts at 0
PFont f; //initailize a font

void setup() {
  size(200, 300);
  noStroke();
  background(0);

  f = loadFont("ComicSansMS-48.vlw"); //Load Font
  textFont(f, 15);                 //Specify font type
  print(Serial.list());
  String[] Avail = Serial.list();
  for(int i =0; i < Avail.length; i++)
  {
    text(Avail[i], 10, 20*i+80); //print text of avaliable serial ports to app
  }

  fill(0,255,0);
  text(Avail[PrtChose], 10, 20*PrtChose+80); //highlite the port in use

  String portName = Serial.list()[PrtChose];
  myPort = new Serial(this, portName, 115200);
}

void draw()
{
  //chnage colors of 4 ellipses according to what keys are pressed
  if (KeyArray[0] == 1)
  {
    fill(0, 255, 0);
  }
  else
  {
    fill(255, 0, 0);
  }
  ellipse(100, 20, 5, 5);

  if (KeyArray[1] == 1)
  {
    fill(0, 255, 0);
  }
  else
  {
    fill(255, 0, 0);
  }
  ellipse(100, 40, 5, 5);

  if (KeyArray[2] == 1)
  {
    fill(0, 255, 0);
  }
  else
  {
    fill(255, 0, 0);
  }
  ellipse(120, 40, 5, 5);

  if (KeyArray[3] == 1)
  {
    fill(0, 255, 0);
  }
  else
  {
    fill(255, 0, 0);
  }
  ellipse(80, 40, 5, 5);
}

void keyReleased() //key released
{
  if (key == 'w') //fwd, fwd has been let up, so set stop fwd message
  {
    KeyArray[0] = 0; //no longer pressed
  }
  if (key == 's') //down
  {
    KeyArray[1] = 0;
  }
  if (key == 'd') //right
  {
    KeyArray[2] = 0;
  }
  if (key == 'a') //left
  {
    KeyArray[3] = 0;
  }

  writeMsg(); //send updated state over serial
}

void keyPressed() //key pressed
{
  if (key == 'w') //fwd
  {
    KeyArray[0] = 1; //fwd key pressed down, set forward command
  }
  if (key == 's') //down
  {
    KeyArray[1] = 1;
  }
  if (key == 'd') //right
  {
    KeyArray[2] = 1;
  }
  if (key == 'a') //left
  {
    KeyArray[3] = 1;
  }

  writeMsg();
}

void writeMsg()
{
  //so both fwd/back, lft/rght dont activate at same time
  if(KeyArray[0] == 1 && KeyArray[1] == 1)
  {
    KeyArray[0] = 0;
    KeyArray[1] = 0;
  }
  if(KeyArray[2] == 1 && KeyArray[3] == 1)
  {
    KeyArray[2] = 0;
    KeyArray[3] = 0;
  }
  //<0,0,0,0>   <fwd,bck,rght,Lft>
  myPort.write("<" + KeyArray[0] + "," + KeyArray[1] + "," + KeyArray[2] + "," + KeyArray[3] + ">"); //write to serial
  println("<" + KeyArray[0] + "," + KeyArray[1] + "," + KeyArray[2] + "," + KeyArray[3] + ">"); //display in console
}

Arduino Code

int started = 0;
char inData[10];
int ended = 0;
char index = 0;
int final = 0;

boolean Fwd = 0;
boolean Bck = 0;
boolean Rght = 0;
boolean Lft = 0;

void setup()
{
  Serial.begin(115200);
  pinMode(13,OUTPUT);
}
void loop()
{
  GetBluData(); //input like: <0,0,0,0> then splits and writes values to F,B,R,L
  TriggerBtn(2,Fwd); //set digital pin 2 to value of Fwd ( HIGH or LOW)
  TriggerBtn(3,Bck);
  TriggerBtn(4,Rght);
  TriggerBtn(5,Lft);
 /*
  Serial.print(Fwd);
  Serial.print(",");
  Serial.print(Bck);
  Serial.print(",");sss
  Serial.print(Rght);
  Serial.print(",");
  Serial.println(Lft);
  */
}

void TriggerBtn(int PinNum, boolean ButtonState)
{
  if(ButtonState)
  {
    //turns on the button connected to the pin
    digitalWrite(13,HIGH); //some key has been pressed, LED to show it

    digitalWrite(PinNum, LOW); // PinNum is the number of the digital pin
    pinMode(PinNum, OUTPUT);  // Pull the signal low to activate button
  }
  else
  {
     //releases button connected to the pin
    digitalWrite(13, LOW); //no key is being pressed, LED to show it

    pinMode(PinNum, INPUT);  // Release the button.
  }
}

void GetBluData()
{
  while(Serial.available() )
  {
  //finds < and >, the beginning and end of command
    char aChar = Serial.read();
    if(aChar == '<')
    {
      started = true;
      index = 0;
      inData[index] = '\0';
    }
    else if(aChar == '>')
    {
      ended = true;
    }

    else if(started)
    {
      inData[index] = aChar;
      index++;
      inData[index] = '\0';          
    }

    else if (aChar =='*')
    {
      final = true;
    }
  }


  if(started && ended)
  {
    const char*  strDelimiter = ",";

    char* p;
    //<0,0,0,0>

//splits to individual ints
    if ( p = strtok(inData, strDelimiter) )  
    {
      Fwd = atoi(p);
    }
    if ( p = strtok(NULL, strDelimiter) )  
    {
      Bck = atoi(p);
    }
    if ( p = strtok(NULL, strDelimiter) )  
    {
      Rght = atoi(p);
    }
    if ( p = strtok(NULL, strDelimiter) )  
    {
      Lft = atoi(p);
    }

    // Get ready for the next time
    started = false;
    ended = false;
    index = 0;
    inData[index] = '\0';    
  }
}


8 comments:

  1. hello, i was wondering if it is possible to connect a h-bridge circuit with transistors to the outgoing arduino output pins which are connected to the rc transmiter, and can you please tell me which are the output pins from the arduino i can't see them in the code

    ReplyDelete
    Replies
    1. pin 2 is forward on the remote...
      TriggerBtn(2,Fwd); //set digital pin 2 to value of Fwd ( HIGH or LOW)
      TriggerBtn(3,Bck);
      TriggerBtn(4,Rght);
      TriggerBtn(5,Lft);

      you dont need a transistor / h bridge to trigger the buttons on the remote:
      if(ButtonState)
      {
      //turns on the button connected to the pin
      digitalWrite(13,HIGH); //some key has been pressed, LED to show it

      digitalWrite(PinNum, LOW); // PinNum is the number of the digital pin
      pinMode(PinNum, OUTPUT); // Pull the signal low to activate button
      }

      but if you mean the arduino pins to the actual motors on the car, then yes.

      Delete
  2. Very useful thing here! Thank you very much for posting it, there is not much stuff like that around the internet!

    ReplyDelete
  3. If I wanted to implement this idea using a MATLAB GUI as the controlller.....what changes would I have to make to either the processing code or the Arduino code? I'm trying to do a 3 phase project. Phase 1 is to control the car remotely (USB), Phase 2 is to control it wirelessly. Phase 3 is to let the vehicle operate somewhat autonomously.

    ReplyDelete
    Replies
    1. for phase 1 if you mean using serial over usb, there wouldnt really be any changes. ive never used mathlab so i have no idea really. sorry.

      Delete
  4. Array out of bound exception error in " text(Avail[PrtChose], 10, 20*PrtChose+90)"

    ReplyDelete
  5. Hi how can I directly connect the arduino uno into the pins of the receiver board instead of the transmitter/controller board?

    ReplyDelete