How to repeat an IF statement

Question

My LCD info is called from an IF statement but since it's clock and temperature info i don't want to just show the information but update the information constantly in real time. i don't want to use (while) loop or any other "code-blocking".

Here's the whole code:

#include <OneWire.h>
#include <LiquidCrystal_I2C.h>
#include <DS3231.h>
#include <DallasTemperature.h>


#define ONE_WIRE_BUS 2
int Heater= 3;
int Switch1= 4;

Time t;
LiquidCrystal_I2C lcd(0x27, 16, 2);
DS3231  rtc(SDA, SCL);
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

// Push button

boolean oldSwitchState = LOW;
boolean newSwitchState = LOW;
boolean lcdScroll = LOW;
boolean lcdBacklight = LOW;
boolean lcdWelcome = LOW;

unsigned long previousMillis = 0;
const long BacklightTime = 10000;

void setup() {
  Serial.begin(115200);
  pinMode(Heater, OUTPUT);
  pinMode(Switch1, INPUT);
  lcd.begin();
  rtc.begin();
}
void loop() {
  float testTemp = sensors.getTempCByIndex(0);
  sensors.requestTemperatures();
  t = rtc.getTime();
  if(lcdWelcome == LOW){
      lcd.setCursor(0,0);
      lcd.print("Welcome, Admin!");
      lcd.setCursor(0,1);
      lcd.print("press Start");
  }

  // LCD
  newSwitchState = digitalRead(Switch1);
    if (millis() - previousMillis >= BacklightTime) {
      lcd.noBacklight();
      lcdBacklight = LOW;
    }
    else if ( lcdBacklight == LOW ){
      lcd.backlight();
      lcdBacklight = HIGH;
    }
    if ( newSwitchState != oldSwitchState ) {
       if ( newSwitchState == HIGH ){
       previousMillis = millis();
       lcdWelcome = HIGH;
       lcd.clear();
      if ( lcdScroll == LOW ){
        lcd.setCursor(0,0);
        lcd.print(testTemp);
        lcd.print("   ");
        lcd.print(rtc.getTimeStr());
        lcdScroll = HIGH;
      }
      else{
        lcd.setCursor(0,0);
        lcd.print(rtc.getDOWStr());
        lcd.print("   ");
        lcd.print(rtc.getDateStr());
        lcdScroll = LOW;
      }
       }
       oldSwitchState = newSwitchState;
    }
}

How can i update the functions inside the if(lcdScroll == LOW){} and else{} statements constantly to show on display?

I'm not clear on what your problem is - I don't see any blocking code here - you test the clock and the switches and either act on them or don't, which is appropriate. Also, what do you mean by "How to repeat an IF statement"? — JRobert
– JRobert, Commented Jun 17, 2019 at 21:33
Also, do not compare values with true, false, 1, 0, or HIGH or LOW, just write if (variable), by default all nonzero values will result in executing the if statement. — Michel Keijzers
– Michel Keijzers, Commented Jun 17, 2019 at 21:42
well your void loop() is already a while loop.....What is it that you are wanting to repeat that is not already happening? — Chad G
– Chad G, Commented Jun 17, 2019 at 22:49
@JRobert the problem is code inside if (lcdScroll == LOW){} only runs once but if i want to have the time to update in real time, time functions have to be in a loop not only run once. — ElectronSurf
– ElectronSurf, Commented Jun 18, 2019 at 5:55

Sim Son · Accepted Answer · 2019-06-18 23:01:16Z

2

Like you suggested in your comment, you can implement a state machine, but the simplest would probably be setting a flag bool a_flag in this if(lcdScroll==LOW) clause and checking if(a_flag) in the highest scope of the loop() section. This is where you print("test");.

In respect to your code this will look like:

bool a_flag=false;
void loop() {
  // some irrelevant stuff
  if ( newSwitchState != oldSwitchState) {
    // some stuff
    if ( lcdScroll == LOW ){
      // stuff you would handle here
      a_flag=true;
    }
    else {
      // stuff you would handle here
      a_flag=false;
    }
  }
  if (a_flag) Serial.println("lcdScroll is LOW");
  else Serial.println("lcdScroll is HIGH");
}

Beside this general solution you could simply do the following in your specific case:

loop(){

  // your actual code

  if (lcdScroll) Serial.println("lcdScroll is LOW");
  else Serial.println("lcdScroll is HIGH");
}

edited Jun 18, 2019 at 23:01

answered Jun 18, 2019 at 8:16

Sim Son

1,87814 silver badges21 bronze badges

i'm very new to this can you please implant that in the code so i can get the whole idea?

ElectronSurf
– ElectronSurf

2019-06-18 09:02:10 +00:00
Commented Jun 18, 2019 at 9:02
@newbie You need to clear this flag somewhere and I'm not sure where (probably in the corresponding else{}). I'll add an implementation of this soon...

Sim Son
– Sim Son

2019-06-18 09:38:49 +00:00
Commented Jun 18, 2019 at 9:38
See my example implementation. This will continuously print the corresponding message. Note also that the backlight will behave erronuously when millis runs over!

Sim Son
– Sim Son

2019-06-18 12:22:35 +00:00
Commented Jun 18, 2019 at 12:22
i asked this question both in reddit and arduino forum and they didn't/couldn't give me an answer. you sir are a legend. thank you and god bless you.

ElectronSurf
– ElectronSurf

2019-06-18 14:29:06 +00:00
Commented Jun 18, 2019 at 14:29

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