gistfile1.cpp

// Just for a laugh I have built 2 more possible versions of the code.
// There is so little code that either way is probably as good as the other,
// but if there were more code then the changes would mean more.

int analogueIn = A0;    //input pin for pressure pad
int digitalOut1 = 8;    //output pin for motor control
int sensorIn;           //variable for triggering the statement in while loop
int primer;             //variable for triggering the primer switch
int primerS = A2;       //input for primer switch
int digitalOut2 = 4;    //output pin for trigger ready LED

// Original Code

void loop ()
{
    primer = analogRead(primerS);
    sensorIn = analogRead(analogueIn); 
    
    if (sensorIn > 400 && primer >=600)     //when the sensor is triggered
    {
        digitalWrite(digitalOut2, LOW);
        digitalWrite(digitalOut1, HIGH);
        delay(500);                          //value to be tested and TBC                      
        digitalWrite(digitalOut1, LOW);
        delay(3000);                         //value to be tested and TBC
    }
    else if (sensorIn < 400 && primer >=600)   //when the sensor is primed
    {
      digitalWrite(digitalOut2, HIGH);
      delay (5);
    }
    else if (primer < 600)    //when the sensor is not primed
    {
      digitalWrite(digitalOut2, LOW);
      delay (5);
    }
}

// Possible version 1.
// Here I have Restructured the IF statements and removed some of the conditions.
// I noticed that you duplicated the condition 'primer >=600' in two of
// your IF statements, so I extracted it out.  Now there are only 2 conditions
// in the code, 'primer >=600' and 'sensorIn > 400', rather than 5 conditions in 
// the original code.

void loop ()
{
    primer = analogRead(primerS);
    sensorIn = analogRead(analogueIn);
    
    if (primer >=600)   // sensor is primed
    {   
      if (sensorIn > 400)     //when the sensor is triggered
      {
        digitalWrite(digitalOut2, LOW);
        digitalWrite(digitalOut1, HIGH);
        delay(500);                          //value to be tested and TBC                      
        digitalWrite(digitalOut1, LOW);
        delay(3000);                         //value to be tested and TBC
      }
      else  
      {
        digitalWrite(digitalOut2, HIGH);
        delay (5);
      }
    } else {
       //when the sensor is not primed
       digitalWrite(digitalOut2, LOW);
       delay (5);
    }
}

// Possible version 2.
// This is probably the version I would use, but  like I said, all versions
// would be fine because there is so little code.

// Here I use the 'return' statement which will return from the function and
// not run the rest of the code.

// A good technique when writing functions is to return quickly if none of the
// basic conditions required for the primary purpose of the function are met.
// The primary purpose of this code is to act as a feeder for an animal by reacting 
// to a pressure pad and opening a feeder, so 
// if the primer on/off switch is not on then we should just quickly exit the function. 
// The main body of the code (the bit that will grow as you add more functionality) 
// should be separate from the primer on/off switch so that this main code is less complex.
// I hope I explained that well enough.

void loop ()
{
    primer = analogRead(primerS);
    sensorIn = analogRead(analogueIn);

    if (primer < 600)   
    {
        // Turn off the light if the primer is not on and leave the function.
        digitalWrite(digitalOut2, LOW);
        delay (5);
        return;
    }
    
    // Main body/purpose of function is seperate from the on/off switch code above :
    
    if (sensorIn > 400)     //when the sensor is triggered
    {
        digitalWrite(digitalOut2, LOW);
        digitalWrite(digitalOut1, HIGH);
        delay(500);                          //value to be tested and TBC                      
        digitalWrite(digitalOut1, LOW);
        delay(3000);                         //value to be tested and TBC
    }
    else  
    {
        digitalWrite(digitalOut2, HIGH);
        delay (5);
    }
}

// Here is a more extreme refactor that I wouldn't do at this stage, it's overkill, but would
// be worth it if it was going to get a lot more complex. 
// Notice that the main loop function is now instantly understandable because of the function names, which 
// is important if you're going to be maintaining complex code.
        
void loop () 
{
    if (!isActive())  {  turnLightOff(); return;  }
 
    if (pressurePadIsTriggered())
    {        
        turnLightOff();
        openTheGate();
        delay(3000); 
    } else {
        turnLightOn();        
    }
}


boolean isActive() 
{
  // primer switch is on.
  return analogRead(primer) >= 600;
}

void turnLightOff() 
{
  digitalWrite(digitalOut2, LOW); // turn/keep light off
  delay (5);
}

boolean pressurePadIsTriggered()  
{
    return sensorIn > 400;
}

void openTheGate() 
{
  // turn on the motor for just 0.5 second
  digitalWrite(digitalOut1, HIGH);
  delay(500);                          
  digitalWrite(digitalOut1, LOW);  
}