Why can't I call a function more than 5 times within an 'if' loop

[milominitug]

My program controls the speed of a diesel engine.
To monitor the RPM I call a function
void measureThrottle (int throttle)
{
throttle = analogRead(A2);
}

I'm finding that I can't call the function more than 5 times within the main 'if else' loop.
If I compile the program with more than 5 calls to the function, it simply stops working.

This has occurred with a second function... same problem can't call the function more than 5 times

[jremington]

Please post ALL the code, using code tags, along with some evidence for your claim.

[aarg]

It's a do-nothing function anyway. It takes the parameter, assigns it to a local variable 'throttle', assigns an analogRead() to it, and then throws the result away as it returns. I would be willing to bet, the rest of the code is full of such errors.

[jremington]

Good point! There is no reason to call that function, ever.

[milominitug]

Ok thanks for the comments but I’m still at a loss. The function’s job is to read the analog input and return with a value in the variable ‘throttle’ . At the end of this listing is the analog read ‘spelt out’ in the code because calling the function the fifth time crashes.

if (digitalRead(engineRunning)== HIGH ) //Start governing speed.
{ //Engine is running. Ignition switch is ON

isEngineRunning = true;
actuatorSpeed = actuatorMaxSpeed;

readRPM(engineRevs);

measureThrottle(throttle);

if (engineRevs < throttle)// Engine speed too slow Retract actuator
{
readRPM(engineRevs);

measureThrottle(throttle);

difference = throttle - engineRevs ;

if (difference < -tolerance1 || difference > tolerance1)
{

readRPM(engineRevs);
measureThrottle(throttle);

difference = throttle - engineRevs ;

digitalWrite(redled, LOW);
digitalWrite(greenled, HIGH);
retractActuator();
}
delay(25);
stopActuator();
digitalWrite(yellowled, HIGH);
}
else
if (engineRevs > throttle)// Engine speed too fast Extend actuator
{
readRPM(engineRevs);

measureThrottle(throttle);

difference = throttle - engineRevs ;

if (difference < -tolerance1 || difference > tolerance1)
{

readRPM(engineRevs);

difference = throttle - engineRevs ;

digitalWrite(redled, HIGH);
digitalWrite(greenled,LOW );
extendActuator();
}
delay(25);
stopActuator();
digitalWrite(yellowled, HIGH);
}

throttle = analogRead(A2); // Read throttle potentiometer value
throttle = (throttle / 10) * 10;

}

}

[jremington]

See reply #1

You need to learn how to write and call functions that return values. Here is just one of many on line tutorials.

[aarg]

The function's job is to read the analog input and return with a value in the variable 'throttle' .

Then you should have passed the variable as a pointer or reference.

[milominitug]

Many thanks. I can see where I've gone wrong now however, strangely, the program worked until the fifth call. lol Thankyou all for your help.