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?

• Juraj: please use true and false as boolean values
• JRobert: 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"?
• Michel Keijzers: 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.
• Chad G: well your void loop() is already a while loop.....What is it that you are wanting to repeat that is not already happening?
• ElectronSurf: @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.

Answer 1

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");
}

• ElectronSurf: i'm very new to this can you please implant that in the code so i can get the whole idea?
• Sim Son: @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: See my example implementation. This will continuously print the corresponding message. Note also that the backlight will behave erronuously when millis runs over!
• ElectronSurf: 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.