How to solve this program error

Question

1.00/5 (1 vote)

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C++

/*  Arduino DC Motor Control - PWM| L293d
*/

#define enA 9
#define in1 4
#define in2 5
#define enB 10
#define in3 6
#define in4 7

int motorSpeedA = 0;
int motorSpeedB = 0;

void setup() {
  pinMode(enA, OUTPUT);
  pinMode(enB, OUTPUT);
  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);
  pinMode(in3, OUTPUT);
  pinMode(in4, OUTPUT);
}
void loop() {
  int 1 button = analogRead(A0);
  int 2 button = analogRead(A1); 
  int 3 button = analogRead(A2); 
  int 4 button = analogRead(A3); // Read value

  // 1,2 button used for forward and backward control
     if (2 button) {
    // Set Motor A backward
    digitalWrite(in1, HIGH);
    digitalWrite(in2, LOW);
    // Set Motor B backward
    digitalWrite(in3, HIGH);
    digitalWrite(in4, LOW);
  }
}
  else if (1 button) {
    // Set Motor A forward
    digitalWrite(in1, LOW);
    digitalWrite(in2, HIGH);
    // Set Motor B forward
    digitalWrite(in3, LOW);
    digitalWrite(in4, HIGH);
  }
  }

  // 3,4 butten used for left and right control
  if (3 button) {
     // Set Motor A forward
    digitalWrite(in1, LOW);
    digitalWrite(in2, HIGH);
    // Set Motor B stop
    digitalWrite(in3, LOW);
    digitalWrite(in4, HIGH);
    }
  if (4 button) {
     // Set Motor A stop
    digitalWrite(in1, LOW);
    digitalWrite(in2, HIGH);
    // Set Motor B forward
    digitalWrite(in3, LOW);
    digitalWrite(in4, HIGH);
    }
  analogWrite(enA, motorSpeedA); // Send PWM signal to motor A
  analogWrite(enB, motorSpeedB); // Send PWM signal to motor B
}

What I have tried:

exit status 1
expected unqualified-id before numeric constant

Posted 23-May-20 9:38am

Member 14841679

Updated 23-May-20 22:42pm

KarstenK

v2

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Rick York · Answer 1 · 2020-05-23T09:48:00

These :

C++

int 1 button = analogRead(A0);
int 2 button = analogRead(A1);
int 3 button = analogRead(A2);
int 4 button = analogRead(A3); // Read value

are not valid expressions.

You could make an array of four integers and do something like this :

C++

int buttons[4];
buttons[0] = analogRead(A0);
buttons[1] = analogRead(A1);
buttons[2] = analogRead(A2);
buttons[3] = analogRead(A3); // Read value

-edit-

Also, as phil.o mentioned, the conditional expressions are incorrect. They need to be of the form :

C++

if( buttons[0] )
{
}
else if( buttons[1] )
{
}

What you wrote for those is not valid in the C or C++ languages. Make sure you understand the differences.

One other thing - usually buttons states are binary with values of 1 or 0. Are you sure it is correct to acquire them using analogRead()? I see you are using digitalWrite, is there a corresponding digitalRead()?