Hi,
Trying to get a small robot to work with an Arduino Uno and a L293D motor driver chip.
Basing our code on this Instructable: http://www.instructables.com/id/Control-your-motors-with-L293D-and-Arduino/?ALLSTEPS
Here is the code we are trying to use:
/*
Michael's first go at coding Arduino
Turns on an LED on for one second, then off for one second, repeatedly.
Controls L293D motor driver chip.
22/6/2016
For Mr T's class
*/
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
Serial.begin(9600);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(500); // wait for a second
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(500); // wait for a second
// Setup motors
int motor_left[] = {2, 3};
int motor_right[] = {7, 8};
int i;
for(i = 0; i < 2; i++){
pinMode(motor_left[i], OUTPUT);
pinMode(motor_right[i], OUTPUT);
}
drive_forward();
delay(1000); // Delay 1 second
motor_stop();
Serial.println("Drive forward to 1");
drive_backward();
delay(1000);
motor_stop();
Serial.println("Drive back to 2");
turn_left();
delay(1000);
motor_stop();
Serial.println("Drive left to 3");
turn_right();
delay(1000);
motor_stop();
Serial.println("Drive right to 4");
motor_stop();
delay(1000);
motor_stop();
Serial.println("Drive nowhere to 5");
}
// --------------------------------------------------------------------------- Drive
void motor_stop(){
digitalWrite(motor_left[0], LOW);
digitalWrite(motor_left[1], LOW);
digitalWrite(motor_right[0], LOW);
digitalWrite(motor_right[1], LOW);
delay(25);
}
void drive_forward(){
digitalWrite(motor_left[0], HIGH);
digitalWrite(motor_left[1], LOW);
digitalWrite(motor_right[0], HIGH);
digitalWrite(motor_right[1], LOW);
}
void drive_backward(){
digitalWrite(motor_left[0], LOW);
digitalWrite(motor_left[1], HIGH);
digitalWrite(motor_right[0], LOW);
digitalWrite(motor_right[1], HIGH);
}
void turn_left(){
digitalWrite(motor_left[0], LOW);
digitalWrite(motor_left[1], HIGH);
digitalWrite(motor_right[0], HIGH);
digitalWrite(motor_right[1], LOW);
}
void turn_right(){
digitalWrite(motor_left[0], HIGH);
digitalWrite(motor_left[1], LOW);
digitalWrite(motor_right[0], LOW);
digitalWrite(motor_right[1], HIGH);
}
However we are getting errors:
'motor_left' was not declared in this scope
(See below for full error.)
HELP! 
We're stuck! Thank you.
Rob.
Arduino: 1.6.9 (Windows 8.1), Board: "Arduino/Genuino Uno"
C:\Users\Jiaren.TANG\Desktop\ET\Arduino_L293D_control_Ver_1\Arduino_L293D_control_Ver_1.ino: In function 'void motor_stop()':
Arduino_L293D_control_Ver_1:76: error: 'motor_left' was not declared in this scope
digitalWrite(motor_left[0], LOW);
^
Arduino_L293D_control_Ver_1:78: error: 'motor_right' was not declared in this scope
digitalWrite(motor_right[0], LOW);
^
C:\Users\Jiaren.TANG\Desktop\ET\Arduino_L293D_control_Ver_1\Arduino_L293D_control_Ver_1.ino: In function 'void drive_forward()':
Arduino_L293D_control_Ver_1:85: error: 'motor_left' was not declared in this scope
digitalWrite(motor_left[0], HIGH);
^
Arduino_L293D_control_Ver_1:87: error: 'motor_right' was not declared in this scope
digitalWrite(motor_right[0], HIGH);
^
C:\Users\Jiaren.TANG\Desktop\ET\Arduino_L293D_control_Ver_1\Arduino_L293D_control_Ver_1.ino: In function 'void drive_backward()':
Arduino_L293D_control_Ver_1:93: error: 'motor_left' was not declared in this scope
digitalWrite(motor_left[0], LOW);
^
Arduino_L293D_control_Ver_1:95: error: 'motor_right' was not declared in this scope
digitalWrite(motor_right[0], LOW);
^
C:\Users\Jiaren.TANG\Desktop\ET\Arduino_L293D_control_Ver_1\Arduino_L293D_control_Ver_1.ino: In function 'void turn_left()':
Arduino_L293D_control_Ver_1:101: error: 'motor_left' was not declared in this scope
digitalWrite(motor_left[0], LOW);
^
Arduino_L293D_control_Ver_1:103: error: 'motor_right' was not declared in this scope
digitalWrite(motor_right[0], HIGH);
^
C:\Users\Jiaren.TANG\Desktop\ET\Arduino_L293D_control_Ver_1\Arduino_L293D_control_Ver_1.ino: In function 'void turn_right()':
Arduino_L293D_control_Ver_1:109: error: 'motor_left' was not declared in this scope
digitalWrite(motor_left[0], HIGH);
^
Arduino_L293D_control_Ver_1:111: error: 'motor_right' was not declared in this scope
digitalWrite(motor_right[0], LOW);
^
exit status 1
'motor_left' was not declared in this scope
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.
Thank you so much! We now have a very happy 'bot running around the place!