stuff.cpp

const uint8_t leds[] = { E6, B1, D0, D1, D2 };

void set_leds(void);
void clear_leds(void);

void keyboard_post_init_user(){
  // Set all 5 LED pins as outputs
  for(int i=0; i<sizeof(leds)/sizeof(leds[0]); i++)
  {
    setPinOutput(leds[i]);
  }  
}

// Turn on all LEDs (active low LEDS)
void set_leds(){
  for(int i=0; i<sizeof(leds)/sizeof(leds[0]); i++)
  {
    writePin(leds[i], 0);
  }  
}

// Turn off all LEDs (active low leds)
void clear_leds(){
  for(int i=0; i<sizeof(leds)/sizeof(leds[0]); i++)
  {
    writePin(leds[i], 1);
  }  
}

bool led_update_kb(led_t led_state) 
{
    bool res = led_update_user(led_state);
    if(res) 
    {
        // writePin sets the pin high for 1 and low for 0.
        // In this example the pins are inverted, setting
        // it low/0 turns it on, and high/1 turns the LED off.
        // This behavior depends on whether the LED is between the pin
        // and VCC or the pin and GND.
        clear_leds();
        uint8_t highest_layer = get_highest_layer(layer_state);
        // If layer is less than 0 (how?!) turn off all leds
        if (highest_layer < 0) 
        {
          clear_leds();
        }
        else if(highest_layer < 5)
        {
          clear_leds();
          writePin(leds[highest_layer], 0); // If layer is between 0 and 4 (inclusive) turn on corrosponding led
        } else 
        {
          set_leds(); // If layer is higher than 4, turn on all LEDs
        }
    }
    return res;
}