Cannot set Pins to LOW

Question

I am controlling 2 motors from my Arduino Pro Mini and L293D motor driver module. Problem is, I have to set a pin high and after 1 second set it to LOW. But that doesn't happen... The pin just stays HIGH and is never LOW.

Here's my Code -

 int IN2Left = 10;
 int E1 = 12;
 int E2 = 7;
 int IN3RevRight = 6;
 int trigPin1 = A0;
 int echoPin1 = A1;
 int distance1 = 0;
 int IN4Right = 5;
 int IN1RevLeft = 11;
 void setup()
 {
 pinMode(IN2Left, OUTPUT);
 pinMode(E1, OUTPUT);
 pinMode(E2, OUTPUT);
 pinMode(IN3RevRight, OUTPUT);
 pinMode(IN4Right, OUTPUT);
 pinMode(IN1RevLeft, OUTPUT);
 pinMode(trigPin1, OUTPUT);
 pinMode(echoPin1, INPUT);
 pinMode(13, OUTPUT);
 Serial.begin(9600);
 }
 void loop() {
 digitalWrite(13, HIGH);
 digitalWrite(E1, HIGH);
 digitalWrite(E2, HIGH);
 digitalWrite(IN2Left, HIGH);
 digitalWrite(IN4Right, HIGH);
 delay(3000);
 digitalWrite(IN4Right, LOW);
 digitalWrite(IN3RevRight,HIGH);
 delay(500);
 digitalWrite(IN3RevRight, LOW);
 digitalWrite(IN4Right, HIGH);
 delay(1500);
 digitalWrite(IN2Left, LOW);
 digitalWrite(IN1RevLeft, HIGH);
 delay(500);
 digitalWrite(IN1RevLeft, LOW);
 digitalWrite(IN2Left, HIGH);
 delay(100000);
 }

The IN2Left Pin never goes LOW... I am assuming a faulty Arduino but my Arduino seems to be working just fine as it runs other stuff (tested blink and reading an Ultrasonic sensor) just fine.

My deadline is 2 hours from now...

EDIT: Here's the complete void loop function... Note the two pins on top which go HIGH? They Never go LOW again in the entire code.

• Nick Gammon: If you load a blank sketch, like int main () { } does the pin in question start off high?
• Gerben: Are you sure there isn't something else connected to pin 10?
• YaddyVirus: @NickGammon No... Its very strange..
• YaddyVirus: @Gerben Too damn sure
• Nick Gammon: I tried your amended code and the pin went low every 1 minute 40 seconds for half a second, which is what you told it to do. You have to watch closely to spot it.

Answer 1

Your code sets it high, delays for 1000ms, sets it low, and then... turns around and sets it high almost immediately after. Try delaying in between.

• Nick Gammon: Beaten by 24 seconds. :)
• YaddyVirus: yeah it does... However, if the LOW command is in an if it never executes even when the if block runs.

Answer 2

 digitalWrite(IN2Left, HIGH);
 delay(1000);
 digitalWrite(IN2Left, LOW);

It would go LOW for a few microseconds. Maybe put a delay after going LOW?

• YaddyVirus: yeah it does... However, if the LOW command is in an if it never executes even when the if block runs...
• KIIV: @YaddyVirus Maybe you are trying to pull down something stronger than output driver. How about using LEDs with series resistors to confirm it (with everything else disconnected)?
• Nick Gammon: if the LOW command is in an if - What are you talking about? There is no if in your code.
• YaddyVirus: @NickGammon Actually I tried various ways of setting pins to LOW... One was to set a condition and accordingly set the pins to LOW.
• Nick Gammon: Try: void setup() { pinMode(10, OUTPUT); digitalWrite (10, LOW); } void loop () {} - is pin 10 low then? If so, you can't say that pin 10 "never" goes low.