Aurdino coding to control a motor - arduino

Question

//Motor A
const int motorpin1 = 6; // Pin 6 of L293
const int motorpin2 = 9; // Pin 3 of L293
void setup() {
pinMode(motorpin1, OUTPUT);
pinMode(motorpin2, OUTPUT);
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, LOW);
Serial.begin(9600);
}
// put your main code here, to run repeatedly:
void loop(){
if(Serial.available()>0)
{
char incomingByte = Serial.read();
Serial.println(incomingByte);
if(incomingByte=='a'){
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, LOW);
delay(200);
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, HIGH);
Serial.println("one way");
}
else if(incomingByte=='s'){
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, LOW);
delay(200);
digitalWrite(motorpin1, HIGH);
digitalWrite(motorpin2, LOW);
Serial.println("other way");
}
else{
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, LOW);
}
}
}
If we input a in the serial monitor the motor should rotate in one direction and if we input s the motor should rotate in another direction but it is not happening the motor is idle but i get the output like this:
a
one way
s
other way
There is no problem with hardware connections.
Could you please help me with this.Thanks in advance

Answer 1

According to the comments in your code, you are conecting arduino-pin-6 to the l293-pin-6, and arduino-pin-9 to the l293-pin-3.
According to this datasheet, the control pins in L293 are: 2, 7, 10, 15. So, I believe you are connecting it wrong. Also the pulses are being done in the wrong order (from HIGH to LOW and so on).
This should be the correct code (please look at the comments in the code):
//Motor A
const int motorpin1 = 6; // Pin 7 of L293
const int motorpin2 = 9; // Pin 2 of L293
const int motorenablepin = 10; // Pin 1 of L293
void setup() {
pinMode(motorpin1, OUTPUT);
pinMode(motorpin2, OUTPUT);
pinMode(motorenablepin, OUTPUT);
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, LOW);
digitalWrite(motorenablepin, HIGH); // we can let it enabled
Serial.begin(9600);
}
// put your main code here, to run repeatedly:
void loop(){
if(Serial.available()>0)
{
char incomingByte = Serial.read();
Serial.println(incomingByte);
if(incomingByte=='a'){
digitalWrite(motorpin1, HIGH);
digitalWrite(motorpin2, LOW);
Serial.println("one way");
}
else if(incomingByte=='s'){
digitalWrite(motorpin1, HIGH);
digitalWrite(motorpin2, LOW);
Serial.println("other way");
}
delay(200);
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, LOW);
}
}
Please note that I added the motorenablepin that was missing. It must be conected to the l293-pin-1.
Also, since the LOW and LOW states are common to the code, you can simplify it as I did.

Answer 2

There was small mistake in the logic:
if(incomingByte=='a'){
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, HIGH);//changed to high
delay(10000);
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, LOW);//changed to low
Serial.println("one way");
}
else if(incomingByte=='s'){
digitalWrite(motorpin1, LOW);
digitalWrite(motorpin2, HIGH);//changed to high
delay(2000);
digitalWrite(motorpin1, LOW);//changed to low
digitalWrite(motorpin2, LOW);