layer-rgb.c

static uint8_t old_layer = 255;
void matrix_scan_user(void) {
  #ifdef RGBLIGHT_ENABLE

  uint8_t new_layer = biton32(layer_state);

  if (old_layer != new_layer) {
    switch (new_layer) {
      case _QWERTY:
        rgblight_mode(13);
        break;

      case _LOWER:
        rgblight_mode(1);
        rgblight_setrgb(0x00, 0xA0, 0xFF);
        break;

      case _RAISE:
        rgblight_mode(1);
        rgblight_setrgb(0xFF, 0x20, 0x00);

        break;

      case _ADJUST:
        rgblight_mode(22);
        rgblight_sethsv(0, 255, 255);
        break;
    }

    old_layer = new_layer;
  }

  #endif //RGBLIGHT_ENABLE
}