Creating a loop for serial monitor output - c++

Question

Small description for you... Using arduino uno I am trying to make it so I press a button to switch on the entire program, not hold down press but press and let it release to make it on then do it again to make it off. While its on it needs to output data given from a LDR every 1 second.
Anyway, in the serial monitor (output of data) I want it to say "off" to start with then say "on" after the button is pressed. I have gotten this far.
My problem is when it is on, i cant figure out how to make it display the LDR light sense amount each second while also testing that if it goes over 500 for example, it should then stop and say alarm triggered. And be able to be switched off after also.
Here is my code:
// Devices attached
const int buttonPin = 2; // Pin that BUTTON uses
const int sensorPin = 0; // Pin that SENSOR uses
// List of dynamic variables
int pushCounter = 0; // counter for the number of button presses
int buttonState = 0; // current state of the button
int lastbuttonState = 0; // previous state of the button
void setup()
{
// Set the BUTTON as an INPUT
pinMode(buttonPin, INPUT);
// Create serial prompt
Serial.begin(9600);
}
void loop()
{
// read the pushbutton current state
buttonState = digitalRead(buttonPin);
// compare the buttonState to its previous state
if (buttonState != lastbuttonState)
{
// if the state has changed, increment the counter
if (buttonState == HIGH)
{
// if the current state is HIGH then the button
// wend from off to on:
pushCounter++;
int sensorValue = 0;
// Divides counter by 2, if remainder (not0), then the following
if (pushCounter % 2 == 0){
analogWrite(sensorPin, HIGH);
Serial.println("Power ON");
sensorValue = analogRead(sensorPin);
Serial.println(sensorValue);
delay(1000);
}
else
{
analogWrite(sensorPin, LOW);
Serial.println("OFF");
}
// Debouncing delay
delay(250);
}
// Save the current BUTTON state as the LAST state
lastbuttonState = buttonState;
}
}

Answer 1

Your requirement seems to be a question of task multithreading. It is not possible in bare arduinos. The arduino is single threaded.
analogRead() does not set the pin to be readable, but it returns the value in that pin.
Use analog A0 instead of digital pin 0
const int sensorPin = A0; // Pin that SENSOR uses
boolean isOn = false;
int sensorValue = 0, pinValue = 0;
void loop()
{
buttonState = digitalRead(buttonPin);
if(buttonState != lastbuttonState && buttonState == HIGH) {
pushCounter++;
lastbuttonState = buttonState;
}
if (pushCounter % 2 == 0){
Serial.println("Power ON");
isOn = true;
} else {
Serial.println("OFF");
isOn = false;
}
if(isOn) {
pinValue = analogRead(sensorPin);
Serial.println(pinValue);
if(pinValue > 500) { Serial.println("Alarm triggered"); }
delay(1000);
}
}