#define TRUE 1
#define FALSE 0
const int numLEDs = 4;
const int GPIO_Pins[] = {0,1,2,3};
const int blinkRate = 500;
static bool flag = TRUE;
void setup() {
  // put your setup code here, to run once:
  //Serial1.begin(115200);
  //Serial1.println("Hello, Raspberry Pi Pico!");
  for(int led=numLEDs;led>=0;led--)
  {
    pinMode(GPIO_Pins[led], OUTPUT);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  for(int led=numLEDs;led>=0;led--)
  {
    controlLEDs(led,flag);
  }
  delay(blinkRate);
  flag = !flag;
}
void controlLEDs(int led, bool state)
{
  if(state==TRUE)
  {
  digitalWrite(GPIO_Pins[led], HIGH);
  delay(300);
  }
  else{
  digitalWrite(GPIO_Pins[led], LOW);
  delay(300);
  }
}