Defining values in Void Setup

Projects General Guidance
1

Hi,
I'm new to this forum - and relatively new to Arduino boards and programming. I wasn't sure what category this topic should come under so if its in the wrong one then I apologise.

Basically, I am creating a program which requires a value based on an external sensor to be recorded so that it can be used at a future point. I will include a copy of the program at the end of this message.

What I want to know is this, is there any way of storing a value in the Void Setup () { section?

I did a small amount of this a couple of years ago, however, I haven't done anything between then and now, nor have I done any programming prior to that occasion. As such I am still very much a beginner and have a lot to learn. Prior to this I have trawled the forum, the internet and the example programs, however, I cannot find the information I am looking for. Thus, I come to this forum as a last resort to see if anyone can help me.

The program is linked.
The values I am attempting to define are SensorLight, SensorDark and gateSenDark. The pins A0 and A1 are connected to two potential dividers (one each) formed of a resistor and LDR. The Button (A2) value will be connected to A2 via button (currently being represented by a wire from the 5V pin to pin A2.

Mitchell

Brockhampton_gate_program_lcd.ino (2.23 KB)

2

Stella123:
is there any way of storing a value in the Void Setup () { section?

Set up runs once. Yes you can read a sensor and store a value in your setup code.

3

...but it is then unavailable to any other function, like loop(), unless you provide a global pointer to it.

In which case, you may as well just have made the variable global.

Please remember to use code tags when posting code.

4

As already said, the easiest way for you to do that is declaring a global variable

5

Variable scope

6

Ok, thanks for the responses.
You say I need to add a global pointer. In laymans terms what is this?

You must understand, I have only got into computers, electronics and microcomputers in the last few months, thus, most of these terms don't make sense to me. Nevertheless, I will learn.

The way I understand it, I could also make the values global by creating them outside the setup or loop codes. However, I need the lcd display which, I also understand, needs to be inside such code. Is this correct or am I talking nonsense?

Cheers Mitchell

P.S. Code tags?

7

Forget that last line. Think I've found the code tags now.

Mitchell

8

Why do you think would want to define a variable inside setup()?

Do you understand what scope means?

9

I have copied the code using code tags to make things easier.

//Brockhampton brewery gate program

int Sensor = A0; // Assigns analog pin 0 to sensor
int gateSen = A1; // Assigns analog pin 1 to gateSen
int Button = A2; //Assigns analog pin 2 to Button
#include <Servo.h>
Servo gate;

#include <LiquidCrystal.h> //Includes LiquidCrystal Library
LiquidCrystal lcd(1, 2, 4, 5, 6, 7); //(rs, enable, d4 d5 d6 d7)

int SensorLight = 0; //stores the value of SensorLight pin
int SensorDark = 0; //stores the value of SensorDark pin
int gateSenDark = 0; //stores the value of gateSenDark pin

void setup() {
  pinMode(Sensor, INPUT); //Sets Sensor pin as an input
  pinMode(gateSen, INPUT); //Sets gateSen pin as an input
  pinMode(Button, INPUT); //Sets the Button pin as an input
  gate.attach(10); //Sets servo control to pin 10
  lcd.begin(16, 2);
  for(analogRead(Button); analogRead(Button) <= 500; lcd.clear(), lcd.print("Record 1st"), lcd.setCursor(0,2), lcd.print("Sensor Value"), delay(100)){
  }
  SensorLight = analogRead(Sensor);
  lcd.clear();
  lcd.print("Recorded 1st");
  delay(5000);
  lcd.clear();
  for(analogRead(Button); analogRead(Button) <= 500; lcd.clear(), lcd.print("Record 2nd"), lcd.setCursor(0,2), lcd.print("Sensor Value"), delay(100)){
  }
  SensorDark == analogRead(Sensor);
  lcd.clear();
  lcd.print("Recorded 2nd");
  delay(5000);
  lcd.clear();
  for(analogRead(Button); analogRead(Button) <= 500; lcd.clear(), lcd.print("Record 3rd"), lcd.setCursor(0,2), lcd.print("Sensor Value"), delay(100)){
  }
  gateSenDark == analogRead(gateSen);
  lcd.clear();
  lcd.print("Recorded 3rd");
  delay(5000);
  lcd.clear();
  lcd.print("Recording");
  lcd.setCursor(0,2);
  lcd.print("Completed");
  gate.write(0);
  delay(10000);
}

void loop() {
  lcd.clear();
  lcd.print("Operating");

  for(analogRead(Sensor); analogRead(Sensor) <= (SensorLight+50); gate.write(0)){
  }
  gate.write(90);
  (delay(6000)); //Waits 6 seconds before continuing with program
  
    for(analogRead(Sensor) && analogRead(gateSen); analogRead(Sensor) >= (SensorDark-50) || analogRead(gateSen) >= (gateSenDark-50); gate.write(90)){
    }
      gate.write(0);
  delay(10000); //Waits 10 seconds before restarting program
}

Mitchell

10 
  for(analogRead(Button); analogRead(Button) <= 500; lcd.clear(), lcd.print("Record 2nd"), lcd.setCursor(0,2), lcd.print("Sensor Value"), delay(100)){
  }
  SensorDark == analogRead(Sensor);

I'm not sure what that for loop is doing (it may be OK, but it looks weird), and I'm pretty sure you didn't want to use == .

11

AWOL:
Why do you think would want to define a variable inside setup()?

Do you understand what scope means?

Not in the slightest.

AWOL:
I'm not sure what that for loop is doing (it may be OK, but it looks weird), and I'm pretty sure you didn't want to use == .

The idea behind the loop is that the code keeps searching for a change in the state of the Button pin whilst external factors are changed. Also, I wanted a visual output via the LCD. The loop is currently working, however, the issue is that it isn't recording a value (so you could be right about the '==').
I try to achieve what I wan by using methods and code that have worked for me before. Up until this point that has worked for me. The rest of the code I know works, however, this may not be the best way of recording the value, hence why I have appealed to the forum.

Mitchell

12 
for (analogRead(Button); analogRead(Button) <= 500; lcd.clear(), lcd.print("Record 1st"), lcd.setCursor(0, 2), lcd.print("Sensor Value"), delay(100)) {
  }

seems to roughly be the equivalent to:

  while (analogRead(button) <= 500) {
    lcd.clear();
    lcd.print("Record 1st");
    lcd.setCursor(0, 2);
    lcd.print("Sensor Value");
    delay(100);
  }

But would more conventionally be written as

  lcd.clear();
  lcd.print("Record 1st");
  lcd.setCursor(0, 2);
  lcd.print("Sensor Value");
  while (analogRead(button) <= 500) {  //wait for button to be pressed??
    delay (100);
  }
13

numRepeat = ++numRepeat; Don't do that.

A simple numRepeat++; is sufficient.

14

Hi,
Out of interest whats the difference?
It appears to work anyway.

Mitchell

15 
 numRepeat = ++numRepeat;

Is the same as...

numRepeat++;
numRepeat = numRepeat;
16

You shouldn't use it, because sooner or later you'll write something like "x = x++;", the result of which is specifically undefined.

The result of "x = ++x;" used to be similarly undefined, but I believe is now defined, but only since C++11.