int value[20];
bool ready = false;


void setup(){

    Serial.begin(9600);
}

void loop(){
    static int i;
    static uint32_t prevMicros;
    if(!ready && micros() - prevMicros >=1000){
        value[i] = analogRead(A0);
        i++;
        prevMicros = micros();
    }

    if(i==20){
        ready = true;
        i = 0;
    }

    if(ready){
        int total = 0;
        for (int i = 0; i < 20; i++){
            total += value[i];
            value[i] = 0;
        }
        float totalFloat = total * 5.0f / 1023.0f;
        totalFloat = totalFloat / 20.0f;

        Serial.println("Vrms = " + String(totalFloat));
        ready = false;
    }
}