Fairly new to Arduino - need help programming a code to control speed of a motor

Projects Programming
1

I'm doing a project for my engineering class in my university and I'm trying to create a car that can change the speed wirelessly via bluetooth. As of right now I have arduino uno, 5V DC motor, L239D Stepper motor driver IC, and HC-05 bluetooth module. I'm confident what I'm trying to achieve is possible because so far I have been able to control the motor to move left and right wirelessly. I just need to learn to code so that it can change speeds.

Simply put, I need to know how to code so that I can open up "Serial Monitor" and input a "speed value" for the motor.

I followed this website: http://www.instructables.com/id/Arduino-Control-DC-Motor-via-Bluetooth/

The current coding looks like this:
int motorPin1 = 3; // pin 2 on L293D IC
int motorPin2 = 4; // pin 7 on L293D IC
int enablePin = 5; // pin 1 on L293D IC
int state;
int flag=0; //makes sure that the serial only prints once the state

void setup() {
// sets the pins as outputs:
pinMode(motorPin1, OUTPUT);
pinMode(motorPin2, OUTPUT);
pinMode(enablePin, OUTPUT);
// sets enablePin high so that motor can turn on:
digitalWrite(enablePin, HIGH);
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
}

void loop() {
//if some date is sent, reads it and saves in state
if(Serial.available() > 0){
state = Serial.read();
flag=0;
}
// if the state is '0' the DC motor will turn off
if (state == '0') {
digitalWrite(motorPin1, LOW); // set pin 2 on L293D low
digitalWrite(motorPin2, LOW); // set pin 7 on L293D low
if(flag == 0){
Serial.println("Motor: off");
flag=1;
}
}
// if the state is '1' the motor will turn right
else if (state == '1') {
digitalWrite(motorPin1, LOW); // set pin 2 on L293D low
digitalWrite(motorPin2, HIGH); // set pin 7 on L293D high
if(flag == 0){
Serial.println("Motor: right");
flag=1;
}
}
// if the state is '2' the motor will turn left
else if (state == '2') {
digitalWrite(motorPin1, HIGH); // set pin 2 on L293D high
digitalWrite(motorPin2, LOW); // set pin 7 on L293D low
if(flag == 0){
Serial.println("Motor: left");
flag=1;
}
}
}

2

First thing to learn is to use     [code] and [/code]  to put your code in its own window.

Weedpharma

3

You could easily get 26 speeds by just using letters.
52 speeds if you make it case-sensitive.

4

Look up the switch-case construct in the Reference page to avoid loads of if-else statements.

5

From the code you appear to be driving two seperate DC motors neither of which are stepper motors.

If you want to control speed you could drive them with a PWM signal, and use analogWrite() see here.