#define RED 6
#define GRN 5
#define BLU 4

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(RED, OUTPUT);
  pinMode(GRN, OUTPUT);
  pinMode(BLU, OUTPUT);
}

void loop() {
  digitalWrite(BLU, LOW);
  digitalWrite(RED, HIGH);
  delay(1000);
  digitalWrite(RED, LOW);
  digitalWrite(GRN, HIGH);
  delay(1000);
  digitalWrite(GRN, LOW);
  digitalWrite(BLU, HIGH);
  delay(1000);
}