Motor rotates only one direction with L293D controller

Question

Hello I have an RC car which has two 3v motors (one for left/right and the other one for forward/back). The left and right motor is working fine but when I try to rotate the other motor it rotates only back. I've tried the motor separately and it works in both direction without the controller.

My code is the following:

int enablePinMotorAF = 3;
int in1PinMotorAF = 5;
int in2PinMotorAF = 6;
int enablePinMotorLR = 11;
int in1PinMotorLR = 10;
int in2PinMotorLR = 9;
boolean reverse = true;

void setup() {
  pinMode(enablePinMotorAF, OUTPUT);
  pinMode(in1PinMotorAF, OUTPUT);
  pinMode(in2PinMotorAF, OUTPUT);
  pinMode(enablePinMotorLR, OUTPUT);
  pinMode(in1PinMotorLR, OUTPUT);
  pinMode(in2PinMotorLR, OUTPUT);
}

void loop() {
  //go forward  ->not working
  analogWrite(enablePinMotorAF, 230);  //max speed
  digitalWrite(in1PinMotorAF, reverse);
  digitalWrite(in2PinMotorAF, !reverse);
  delay(3000);
  //go back -> working
  analogWrite(enablePinMotorAF, 230); //max speed
  digitalWrite(in1PinMotorAF, !reverse);
  digitalWrite(in2PinMotorAF, reverse);
  delay(3000);
  //go right -> working
  analogWrite(enablePinMotorLR, 230); //max speed
  digitalWrite(in1PinMotorLR, !reverse);
  digitalWrite(in2PinMotorLR, reverse);
  delay(3000);
  //go left  -> working
  analogWrite(enablePinMotorLR, 230); //max speed
  digitalWrite(in1PinMotorLR, reverse);
  digitalWrite(in2PinMotorLR, !reverse);
  delay(3000);
}

Here is the wiring too:

Wiring

The green and orange wires are for a Bluetooth module.

Do you have any idea how can I solve this problem and to make it work?

Thank you.

Answer 1

To reverse the motors, you need four pins, two for each motor. On a readily-available L293 module, they are often labeled IN1, IN2, IN3, and IN4.

To make one motor go forward, you might set IN1 to 5V and IN2 to 0V. To reverse it, simply switch the inputs, IN1 to 0V and IN2 to 5V. In this case 5V is a digitalWrite(pin, HIGH).

Similar for the other two pins for the other motor. I start my answer with this because the wiring of what output pins to what input pins is vitally important.

The Enable pins is where you've gone wrong, it seems. Enable2 and Enable1 should be connected to the pins to which you're doing the analogWrite() but enablePinMotorAF = 3 for example connects to a motor signal input, not to Enable2 as it probably should. Start with fixing that... your two pins 3 and 11 should be connected to Enable1 and Enable2. You only need PWM on the Enable pins. The others should simply be activated with digitalWrite().

Once you get the Enable n pins connected to PWM, then you'll have a good PWM enable signal. Simply connect the other pins on the same side of the chip (IN1 and IN2 for Enable1 and IN3 and IN4 for Enable2), and turn them on and off with `digitalWrite(pin, HIGH) and you'll be good to go.