#define LEDtop 9
#define LEDmid 10
#define LEDbot 11
#define POT A1
int pot;

void setup() {
    pinMode(LEDtop, OUTPUT);
    pinMode(LEDmid, OUTPUT);
    pinMode(LEDbot, OUTPUT);
    pot=0;
}

void loop() {
    dimmer(LEDtop);
}

void dimmer(byte LED) {
    pot = analogRead(POT);
    pot = map(pot, 0, 1023, 0, 255);
    analogWrite(LED, pot);
}

void fxRes(byte LED) {
    for (byte i=20; i<255; i++) {
    analogWrite(LED, i);
    delay(5);
    }
    for (byte i=255; i>20; i--) {
        analogWrite(LED, i);
        delay(5);
    }
}