/********************************************************************************
   Here's a code sample in C for the ESP32-C2 to implement 
a LED chaser that starts from pin 0 to pin 15, and 
alternates between turning on only even-numbered pins and only
 odd-numbered pins after 20 cycles:


 This code uses the Arduino.h library, which provides a lot 
 of helpful functions for working with the ESP32-C2.
  In the setup function, all of the pins in the 
  pins[] array are configured as outputs.
   The loop function implements the LED chaser
  behavior as described in your requirement.
 created by arvind patil 13 feb2023


*************************************************************************************/ 

#include <Arduino.h>

const int numPins = 16;
int pins[numPins] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};

void setup() {
  for (int i = 0; i < numPins; i++) {
    pinMode(pins[i], OUTPUT);
  }
}

void loop() {
  for (int cycle = 0; cycle < 3; cycle++) {
    for (int i = 0; i < numPins; i++) {
      digitalWrite(pins[i], HIGH);
      delay(500);
      digitalWrite(pins[i], LOW);
    }
  }

  for (int cycle = 0; cycle < 3; cycle++) {
    for (int i = 0; i < numPins; i++) {
      if (i % 2 == 0) {
        digitalWrite(pins[i], HIGH);
      }
    }
    delay(100);
    for (int i = 0; i < numPins; i++) {
      if (i % 2 == 0) {
        digitalWrite(pins[i], LOW);
      }
    }
  }

  for (int cycle = 0; cycle < 3; cycle++) {
    for (int i = 0; i < numPins; i++) {
      if (i % 2 != 0) {
        digitalWrite(pins[i], HIGH);
      }
    }
    delay(100);
    for (int i = 0; i < numPins; i++) {
      if (i % 2 != 0) {
        digitalWrite(pins[i], LOW);
      }
    }
  }
}