I'm new to Arduino and embedded, but understand that it is often better to use global instead of local variables (such as here or here).
I have this simple code (from here):
//Libraries
#include <DHT.h>;
//Constants
#define DHTPIN 2 // what pin we're connected to
#define DHTTYPE DHT22 // DHT 22 (AM2302)
DHT dht(DHTPIN, DHTTYPE); //// Initialize DHT sensor for normal 16mhz Arduino
//Variables
float hum; //Stores humidity value
float temp; //Stores temperature value
void setup()
{
Serial.begin(9600);
dht.begin();
}
void loop()
{
//Read data and store it to variables hum and temp
hum = dht.readHumidity();
temp= dht.readTemperature();
//Print temp and humidity values to serial monitor
Serial.print("Humidity: ");
Serial.print(hum);
Serial.print(" %, Temp: ");
Serial.print(temp);
Serial.println(" Celsius");
delay(2000); //Delay 2 sec.
}
My ancient C programmer training (Unix servers) says I must move variables hum and temp to loop(), or is it better on Arduino to leave them as globals?