digital Thermometer

Projects General Guidance
1

I have created this code for a digital thermometer that I am making. It works fine as is but I need to add a switch to change between F and C instead of just displaying F. Can i add a switch input and then have it skip the C steps if its F or vice versa? I'm very new to the arduino and programming as a whole so thank you for your help.

#include <DHT.h>  //Including the temp sensor library
#include <DHT_U.h>

#include <Adafruit_Sensor.h>


#include "LiquidCrystal.h" // Including the LCD library

#define DHTPIN 6      // Declares pin 6 for communicating with the DHT22 sensor
#define DHTTYPE DHT22 // Declares the type of DHT sensor we are using (DHT22)

DHT dht(DHTPIN, DHTTYPE);          // Declares the DHT connection and type
LiquidCrystal lcd(12,11,10,9,8,7); // Declares the LCD connections

int Fan_Pin1 = 4;  // pin 2 on L293D
int Fan_Pin2 = 3;  // pin 7 on L293D
int Enable = 5;      // pin 1 on L293D 
int LED = 2;        //pin 1 on LED
int Alarm = 13;     // pin 1 on alarm

void setup() {
 pinMode(Fan_Pin1, OUTPUT);  //setting up fan, led, and alarm as outputs
 pinMode(Fan_Pin2, OUTPUT);
 pinMode(Enable, OUTPUT);
 pinMode(LED, OUTPUT);
 pinMode(Alarm, OUTPUT);
 lcd.begin(16,2); // Initializes the LCD
 dht.begin();     // Initializes DHT22 temp sensor
}

void loop() {
 lcd.clear();  // Clear the LCD

 float temp = dht.readTemperature(); // Reading the temperature in Celsius
 float degF = temp * 9 / 5 + 32; //converting celsius reading to fahrenheit
 
 if (isnan(degF)) {  // Validating received data
   lcd.print("Failed to read");
   delay(1000);   // Delays by 1 second
   return;
 }

 lcd.setCursor(0,0);
 lcd.print("Temp: ");  //Writes "Temp: " in the first row
 lcd.print(degF);      // Writes the recieved temperature in the first row
 lcd.print(" F");      //Writes " F" after the actual temperature
 lcd.setCursor(0,1);   // Sets the second row to display the fan speed

 if(degF <75 ) {          // If the temperature less than 75
   analogWrite(Enable,0); // 0% PWM duty cycle
   lcd.print("Fan OFF "); // Prints that the fan is off on LCD  
   delay(100);
 }
else if(degF>=76) {                // If the temperature is above 76
   analogWrite(Enable, 255);        // 100% duty cycle
   lcd.print("Fan Speed: 100%   ");
   delay(100);
 }
else if(degF>=90) {                // If the temperature is above 90
   analogWrite(Enable, 255);        // 100% duty cycle
   lcd.print(" SHUT DOWN NOW!! ");
   digitalWrite(LED, HIGH);  // Turns on warning LED
   digitalWrite(Alarm, HIGH);  //Sounds the warning alarm
   delay(100);
 }
 digitalWrite(Fan_Pin1, LOW);  // To drive the fan in a particular direction
 digitalWrite(Fan_Pin2, HIGH); // To drive the fan in a particular direction

 delay(2000); // 2 seconds delay
}
2

Try this code with some modifications but it's not complete!!

#include <DHT.h>  //Including the temp sensor library
#include <DHT_U.h>

#include <Adafruit_Sensor.h>


#include "LiquidCrystal.h" // Including the LCD library

#define DHTPIN 6      // Declares pin 6 for communicating with the DHT22 sensor
#define DHTTYPE DHT22 // Declares the type of DHT sensor we are using (DHT22)

DHT dht(DHTPIN, DHTTYPE);          // Declares the DHT connection and type
LiquidCrystal lcd(12,11,10,9,8,7); // Declares the LCD connections

const byte Fan_Pin1  = 4;      // pin 2 on L293D
const byte Fan_Pin2  = 3;      // pin 7 on L293D
const byte Enable    = 5;      // pin 1 on L293D 
const byte LED       = 2;      // pin 1 on LED
const byte Alarm     = 13;     // pin 1 on alarm
const byte changeTmp = 6;      // pin 6 change Temperature
bool flagTmp = false;          // true = Celcius false = Farenheith
bool status, statusLast = false;

void setup() {
  pinMode(Fan_Pin1, OUTPUT);  //setting up fan, led, and alarm as outputs
  pinMode(Fan_Pin2, OUTPUT);
  pinMode(Enable, OUTPUT);
  pinMode(LED, OUTPUT);
  pinMode(Alarm, OUTPUT);
  pinMode(changeTmp, INPUT_PULLUP); // push button between GND and pin 6

  lcd.begin(16,2); // Initializes the LCD
  dht.begin();     // Initializes DHT22 temp sensor
}

void loop() {
  lcd.clear();  // Clear the LCD

  float temp = dht.readTemperature(); // Reading the temperature in Celsius
  float degF = temp * 9 / 5 + 32; //converting celsius reading to fahrenheit

  if (isnan(degF)) {  // Validating received data
    lcd.print("Failed to read");
    delay(1000);   // Delays by 1 second
    return;
  }
  status = digitalRead(changeTmp);
  if (status && !statusLast)
      flagTmp = !flagTmp;

  statusLast = status;

  lcd.setCursor(0,0);

  lcd.print("Temp: ");  //Writes "Temp: " in the first row
  if (flagTemp) {
        lcd.print(temp);
        lcd.print(" C");      //Writes " F" after the actual temperature
  }
  else {
      lcd.print(degF);      // Writes the recieved temperature in the first row
      lcd.print(" F");      //Writes " F" after the actual temperature
  }
  lcd.setCursor(0,1);   // Sets the second row to display the fan speed

  // Continue modifications
  
  if (degF <75 ) {          // If the temperature less than 75
      analogWrite(Enable,0); // 0% PWM duty cycle
      lcd.print("Fan OFF "); // Prints that the fan is off on LCD  
      delay(100);
  }
  else if (degF >= 76) {                // If the temperature is above 76
          analogWrite(Enable, 255);        // 100% duty cycle
          lcd.print("Fan Speed: 100%   ");
          delay(100);
  }
else if(degF>=90) {                // If the temperature is above 90
    analogWrite(Enable, 255);        // 100% duty cycle
    lcd.print(" SHUT DOWN NOW!! ");
    digitalWrite(LED, HIGH);  // Turns on warning LED
    digitalWrite(Alarm, HIGH);  //Sounds the warning alarm
    delay(100);
  }
  digitalWrite(Fan_Pin1, LOW);  // To drive the fan in a particular direction
  digitalWrite(Fan_Pin2, HIGH); // To drive the fan in a particular direction

  delay(2000); // 2 seconds delay
}