Arduino as gateopener - arduino

Question

I am new to codeing arduino.
I have a project which is about useing an arduino as a gate opener, but only when the temperature gets above 24 degrees.
The problem is how do i get the arduino to send a signal to the relay to open, but only once?
I tried with if statements and trying under there to run with some while(1); but that seems to end the whole script. so that does not do what i want it to..
```
float temp;
int tempPin = A0;
int Relay1 = 13;
bool ronce = false;
void setup() {
Serial.begin(9600);
pinMode(Relay1,OUTPUT);
}
void loop() {
delay(500);
temp = analogRead(tempPin);
temp = temp * 0.48828125;
Serial.print(temp);
if(temp>24){
ronce == true;
Serial.println(" Temp over 24 degree");
if (ronce = true){
Serial.println(" Ronce is true.");
while(1){
Serial.println("runOnce");
digitalWrite(Relay1,HIGH);
delay(500);
digitalWrite(Relay1,LOW);
}
}
}
else {
ronce == false;
Serial.println(" failure");
}
}
I want it to send a signal at 24 degrees to the relay to go on NC & ground and then turn off after 500 ms ish.
then it should not turn on again until when it gets below 24 degrees again.
The output turns out between 20-37 degrees so the LM35 does as i want it to, it is just the code.

Answer 1

You just need to create a read function and then read it until it reaches above 24, then just turn on relay and wait again until the temp gets below 24.
int tempPin = A0;
int Relay1 = 13;
float read_temp()
{
float sum = 0;
float temp;
for (int i = 0; i < 500; i++)
{
sum += analogRead(tempPin);
delayMicroseconds(100);
}
temp = sum / 500;
temp = temp * 0.48828125;
return temp;
}
void setup()
{
Serial.begin(9600);
pinMode(Relay1, OUTPUT);
}
void loop()
{
if (read_temp() > 24)
{
Serial.println("Temp over 24 degree");
digitalWrite(Relay1, HIGH);
delay(500);
digitalWrite(Relay1, LOW);
// wait until temp reach below 23.5
while (read_temp() > 23.5)
;
}
}