QMK files for KeyboardIO Atreus modified with layer-indicating WS2812 RGB LED

config.h

#define RGB_DI_PIN B2
#define RGBLED_NUM 1

// https://github.com/qmk/qmk_firmware/blob/master/docs/ws2812_driver.md
//#define WS2812_TRST_US 280
//#define WS2812_BYTE_ORDER WS2812_BYTE_ORDER_GRB
#define RGBLIGHT_LIMIT_VAL 63

#define RGBLIGHT_LAYERS

//#define RGBLIGHT_EFFECT_RGB_TEST
//#define RGBLIGHT_EFFECT_BREATHING

#define NO_DEBUG
#define NO_PRINT

keymap.c

// Modified from the KeyboardIO layout
// Ed Nisley - KE4ZNU

#include QMK_KEYBOARD_H

enum layer_names {
    _BASE,
    _SHIFTS,
    _FUNCS,
    _NLAYERS
};

// Tap Dance

enum {
    TD_SPC_ENT,
};

qk_tap_dance_action_t tap_dance_actions[] = {
    [TD_SPC_ENT] = ACTION_TAP_DANCE_DOUBLE(KC_SPC, KC_ENT),
};


// Layer lighting

// Undefine this to enable simple test mode
// Also put #define RGBLIGHT_EFFECT_RGB_TEST in config.h

#define LED_LL

#ifdef LED_LL

const rgblight_segment_t PROGMEM ll_0[] = RGBLIGHT_LAYER_SEGMENTS( {0,1,HSV_WHITE} );
const rgblight_segment_t PROGMEM ll_1[] = RGBLIGHT_LAYER_SEGMENTS( {0,1,HSV_MAGENTA} );
const rgblight_segment_t PROGMEM ll_2[] = RGBLIGHT_LAYER_SEGMENTS( {0,1,HSV_CYAN} );
const rgblight_segment_t PROGMEM ll_3[] = RGBLIGHT_LAYER_SEGMENTS( {0,1,HSV_BLUE} );
const rgblight_segment_t PROGMEM ll_4[] = RGBLIGHT_LAYER_SEGMENTS( {0,1,HSV_GREEN} );
const rgblight_segment_t PROGMEM ll_5[] = RGBLIGHT_LAYER_SEGMENTS( {0,1,HSV_RED} );
const rgblight_segment_t PROGMEM ll_6[] = RGBLIGHT_LAYER_SEGMENTS( {0,1,HSV_YELLOW} );

const rgblight_segment_t* const PROGMEM ll_layers[] = RGBLIGHT_LAYERS_LIST(
    ll_0,ll_1,ll_2,ll_3,ll_4,ll_5,ll_6
);

#endif

void keyboard_post_init_user(void) {

#ifdef LED_LL
    rgblight_layers = ll_layers;
    rgblight_set_layer_state(0, 1);
#else
    rgblight_enable_noeeprom();
    rgblight_mode_noeeprom(RGBLIGHT_MODE_RGB_TEST);
//    rgblight_mode_noeeprom(RGBLIGHT_MODE_BREATHING + 3);
#endif

}


#ifdef LED_LL

layer_state_t layer_state_set_user(layer_state_t state) {
    for (uint8_t i=0 ; i < _NLAYERS; i++)
        rgblight_set_layer_state(i, layer_state_cmp(state, i));

    return state;
}
#endif


// Key maps

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
  [_BASE] = LAYOUT(                             // base layer for typing
    KC_Q,    KC_W,    KC_E,    KC_R,    KC_T,                      KC_Y,    KC_U,    KC_I,    KC_O,    KC_P    ,
    KC_A,    KC_S,    KC_D,    KC_F,    KC_G,                      KC_H,    KC_J,    KC_K,    KC_L,    KC_SCLN ,
    KC_Z,    KC_X,    KC_C,    KC_V,    KC_B,    KC_GRV,  KC_LALT, KC_N,    KC_M,    KC_COMM, KC_DOT,  KC_SLSH ,
    LT(_FUNCS,KC_ESC), KC_TAB, KC_LGUI,  KC_BSPC, KC_LSFT,  KC_LCTL, KC_ENT , TD(TD_SPC_ENT),  MO(_SHIFTS), KC_MINS, KC_QUOT, KC_BSLS),

  [_SHIFTS] = LAYOUT(                           // shifted chars and numpad
    KC_EXLM, KC_AT,   KC_UP,   KC_DLR,  KC_PERC,                  KC_PGUP, KC_7,    KC_8,   KC_9, KC_HOME,
    KC_LPRN, KC_LEFT, KC_DOWN, KC_RGHT, KC_RPRN,                  KC_PGDN, KC_4,    KC_5,   KC_6, KC_END,
    KC_LBRC, KC_RBRC, KC_HASH, KC_LCBR, KC_RCBR, KC_CIRC, KC_AMPR,KC_ASTR, KC_1,    KC_2,   KC_3, KC_PLUS,
    KC_NO  , KC_INS,  KC_LGUI, KC_DEL , KC_BSPC, KC_LCTL, KC_LALT,KC_SPC,  KC_TRNS, KC_DOT, KC_0, KC_EQL ),

  [_FUNCS] = LAYOUT(                            // function keys
    KC_INS,  KC_HOME, KC_UP,   KC_END,  KC_PGUP,                   KC_UP,   KC_F7,   KC_F8,   KC_F9,   KC_F10  ,
    KC_DEL,  KC_LEFT, KC_DOWN, KC_RGHT, KC_PGDN,                   KC_DOWN, KC_F4,   KC_F5,   KC_F6,   KC_F11  ,
    KC_NO,   KC_VOLU, KC_NO,   KC_NO,   RESET,   _______, _______, KC_NO,   KC_F1,   KC_F2,   KC_F3,   KC_F12  ,
    KC_NO,   KC_VOLD, KC_LGUI, KC_LSFT, KC_BSPC, KC_LCTL, KC_LALT, KC_SPC,  TO(_BASE), KC_PSCR, KC_SLCK, KC_PAUS )
};

rules.mk

AUTO_SHIFT_ENABLE = yes			# allow automagic shifting
TAP_DANCE_ENABLE = yes			# allow multi-tap keys

RGBLIGHT_ENABLE = yes			# addressable LEDs

More details on my blog at https://wp.me/poZKh-9Iv