Use Android smartphone to control two wheels robot with Arduino via Bluetooth

2) Arduino Programming Part

For the Arduino programming part, I'm using is Arduino Leonardo. The difference of programming coding of Leonardo with Uno is the "serial" command. If i'm not mistaken, for Leonardo to communicate via Bluetooth the command will be "Serial1.xx" as below. Meanwhile for Uno will be just "Serial.xx".

Before going into Arduino programming part, you have to configure your own Bluetooth module. For example: set the baudrate, name of the Bluetooth device, and password to let your Android device connect to your Bluetooth shield. I'm doing all this setting by using a software called hyperterminal. You can try to configure your bluetooth module first because everyone are using different shield & module so I'm not gonna emphasize on it here, you can always try to google it :) (Bluetooth module configuration). Also, make sure your computer had installed the correct driver for your own Bluetooth Dongle.

Bluetooth Shield, Module and Dongle that I'm using

Below are the coding for my Arduino Leonardo: 

#include <Servo.h> //include servo function

#define BUFFERSIZE 127

uint8_t inBuffer[BUFFERSIZE];

int inLength; // length of data in the buffer

int numLoop = 0; // number of times we looped

char val;

Servo myservo;  //for servo function

int motor_LF=2; //declaring pin used for the motor

int motor_LR=3;

int motor_RF=4;

int motor_RR=5;

int motor_LPWM = 13; //declaring pwm pin

int motor_RPWM = 11;

void setup() {

  Serial1.begin(38400); //baud rate I set for bluetooth module is 38400

  myservo.attach(9); //my servo at pin 9 as actuator

  pinMode(motor_LF, OUTPUT); //set pin as output

  pinMode(motor_LR, OUTPUT);

  pinMode(motor_RF, OUTPUT);

  pinMode(motor_RR, OUTPUT);

  pinMode(motor_LPWM, OUTPUT);

  pinMode(motor_RPWM, OUTPUT);

 

  motor_reset(); // call function to reset the motor

}

void loop() {

  // read string if available

  if (Serial1.available()) {

    inLength =  0;

    while (Serial1.available()) {

      val = Serial1.read();

    }

   

    Serial1.print("Arduino received: "); //send the text to the android device

    Serial1.write(val);

    Serial1.println();

  }

 

   if (val == 'k') //K

    { myservo.write(90); } //write the angle of servo should move

   

    if (val == 'l') //L

    { myservo.write(30); }

   

      if (val == 'm') ///M

    { myservo.write(178); }

   

    if (val == 'w') //W – Forward motion of motor

    {

      digitalWrite(motor_LF, HIGH);

      digitalWrite(motor_LR, LOW);

      digitalWrite(motor_RF, HIGH);

      digitalWrite(motor_RR, LOW);

      analogWrite(motor_LPWM, 255); //sending pwm pulses

      analogWrite(motor_RPWM, 255); //255 will be highest

    }

   

    if (val == 's') //S – Reverse motion

    {

      digitalWrite(motor_LF, LOW);

      digitalWrite(motor_LR, HIGH );

      digitalWrite(motor_RF, LOW);

      digitalWrite(motor_RR, HIGH);

      analogWrite(motor_LPWM, 255);

      analogWrite(motor_RPWM, 255);

}

    if (val == 'q') //Q - Left Forward

    {

      digitalWrite(motor_LF, HIGH);

      digitalWrite(motor_LR, LOW);

      digitalWrite(motor_RF, HIGH);

      digitalWrite(motor_RR, LOW);

      analogWrite(motor_LPWM, 128); //slower thn Right PWM but same direction to turn left

      analogWrite(motor_RPWM, 255);

    }

   

    if (val == 'e') //E - Right Forward

    {

      digitalWrite(motor_LF, HIGH);

      digitalWrite(motor_LR, LOW);

      digitalWrite(motor_RF, HIGH);

      digitalWrite(motor_RR, LOW);

      analogWrite(motor_LPWM, 255);

      analogWrite(motor_RPWM, 128); //slower thn left PWM but same direction to turn right

    }

        if (val == 'z') //Z - Left backward

    {

      digitalWrite(motor_LF, LOW);

      digitalWrite(motor_LR, HIGH);

      digitalWrite(motor_RF, LOW);

      digitalWrite(motor_RR, HIGH);

      analogWrite(motor_LPWM, 128);

      analogWrite(motor_RPWM, 255);

    }

        if (val == 'c') //C - Right backward

    {

      digitalWrite(motor_LF, LOW);

      digitalWrite(motor_LR, HIGH);

      digitalWrite(motor_RF, LOW);

      digitalWrite(motor_RR, HIGH);

      analogWrite(motor_LPWM, 255);

      analogWrite(motor_RPWM, 128);

    }

   

    if (val == 'a') //A - Spin Left

    {

      digitalWrite(motor_LF, LOW);

      digitalWrite(motor_LR, HIGH);

      digitalWrite(motor_RF, HIGH);

      digitalWrite(motor_RR, LOW);

      analogWrite(motor_LPWM, 255); //move in same speed but different direction to spin

      analogWrite(motor_RPWM, 255);

    }

   

    if (val == 'd') //D - Spin Right

    {

      digitalWrite(motor_LF, HIGH);

      digitalWrite(motor_LR, LOW);

      digitalWrite(motor_RF, LOW);

      digitalWrite(motor_RR, HIGH);

      analogWrite(motor_LPWM, 255);

      analogWrite(motor_RPWM, 255);

    }

    if (val == ' ') //Space – Brake function

    {

      digitalWrite(motor_LF, LOW); //make all the pin LOW to stop the motor

      digitalWrite(motor_LR, LOW);

      digitalWrite(motor_RF, LOW);

      digitalWrite(motor_RR, LOW);

      analogWrite(motor_LPWM, 255); //both 255 to make the motor stop immediately

      analogWrite(motor_RPWM, 255);

    }

   

    if (val == 't') //T – Reset the motor

    {

      motor_reset();

    }

 

}

void motor_reset()  //reset function

{

  digitalWrite(motor_LF, LOW);

  digitalWrite(motor_LR, LOW);

  digitalWrite(motor_RF, LOW);

  digitalWrite(motor_RR, LOW);

  analogWrite(motor_LPWM, 0);

  analogWrite(motor_RPWM, 0);

}//END of arduino code

Parts of the coding credits to

Nadrew Chong Jia Ying