diff --git a/gong1/platformio.ini b/gong1/platformio.ini
new file mode 100644
index 0000000..bfecb36
--- /dev/null
+++ b/gong1/platformio.ini
@@ -0,0 +1,43 @@
+; < NOTE >
+
+; to enable verbose output add option -->
+; $ platformio run --verbose
+
+; to make this permanent for the proj. -->
+; $ platformio settings set force_verbose Yes
+
+; then confirm the change -->
+; $ platformio settings get
+
+
+; // pio v 4.0 'Build options'
+;    - build_type
+;    - build_flags
+;    - src_build_flags
+;    - build_unflags
+;    - src_filter
+;    - targets
+
+
+[platformio]
+default_envs = d1_mini_pro
+
+[env]
+framework = arduino
+upload_port = /dev/ttyUSB0
+lib_deps =
+  721 ; TaskScheduler
+
+[env:nodemcuv2]
+platform = espressif8266
+board = nodemcuv2
+lib_deps =
+  ${env.lib_deps}
+upload_speed = 921600 ; 9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600
+
+[env:d1_mini_pro]
+platform = espressif8266
+board = d1_mini_pro
+lib_deps =
+  ${env.lib_deps}
+upload_speed = 460800 ; 9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600
diff --git a/gong1/src/main.cpp b/gong1/src/main.cpp
new file mode 100644
index 0000000..f64a764
--- /dev/null
+++ b/gong1/src/main.cpp
@@ -0,0 +1,336 @@
+//
+// wirelessly connected cloud (based on ESP-NOW, a kind of LPWAN?)
+//
+
+//
+// Conversation about the ROOT @ SEMA storage, Seoul
+//
+
+//
+// 2021 02 15
+//
+//   this module will be an esp-now node in a group.
+//       like, a bird in a group of birds.
+//
+//   esp-now @ esp8266 w/ broadcast address (FF:FF:FF:FF:FF:FF)
+//       always broadcasting. everyone is 'talkative'.
+//
+
+// then, let it save a value in EEPROM (object with memory=mind?)
+
+//============<identities>============
+//
+#define MY_GROUP_ID   (5000)
+#define MY_ID         (MY_GROUP_ID + 1)
+#define MY_SIGN       ("GONG1")
+//
+//============</identities>============
+
+//==========<list-of-configurations>===========
+//
+// 'HAVE_CLIENT'
+// --> i have a client. enable the client task.
+//
+// 'SERIAL_SWAP'
+// --> UART pin swapped.
+//     you want this, when you want a bi-directional comm. to external client boards (e.g. teensy).
+//
+// 'DISABLE_AP'
+// --> (questioning)...
+//
+// 'HAVE_CLIENT_I2C'
+// --> i have a client w/ I2C i/f. enable the I2C client task.
+//
+//==========</list-of-configurations>==========
+//
+// (EMPTY)
+
+//============<gonggong>============
+// #define GONG_SIDE_KEY      1000 // X1 = start angle, X2 = hit angle
+#define GONG_MOVE_KEY      1001 // X3 = set angle
+// #define GONG_HEAD_KEY      1002 // random (HEAD)
+//============</gonggong>===========
+
+//============<parameters>============
+//
+#define LED_PERIOD (11111)
+#define LED_ONTIME (1)
+#define LED_GAPTIME (222)
+//
+#define WIFI_CHANNEL 5
+//
+// 'MONITORING_SERIAL'
+//
+// --> sometimes, the 'Serial' is in use (for example, 'osc' node)
+//     then,      use 'Serial1' - D4/GPIO2/TDX1 @ nodemcu (this is TX only.)
+//
+// --> otherwise, MONITORING_SERIAL == Serial.
+//
+#if defined(SERIAL_SWAP)
+#define MONITORING_SERIAL (Serial1)
+#else
+#define MONITORING_SERIAL (Serial)
+#endif
+//
+//============</parameters>===========
+
+//============<board-specifics>============
+#if defined(ARDUINO_FEATHER_ESP32) // featheresp32
+#define LED_PIN 13
+#else
+#define LED_PIN 2
+#endif
+//============</board-specifics>===========
+
+//arduino
+#include <Arduino.h>
+
+//post & addresses
+#include "../../post.h"
+
+//espnow
+#include <ESP8266WiFi.h>
+#include <espnow.h>
+
+//task
+#include <TaskScheduler.h>
+Scheduler runner;
+
+//-*-*-*-*-*-*-*-*-*-*-*-*-
+// servo
+#include <Servo.h>
+
+// my tasks
+
+// servo. - common
+static Servo servo;
+extern Task servo_release_task;
+void servo_release() {
+  servo.detach();
+}
+Task servo_release_task(0, TASK_ONCE, &servo_release);
+
+// gong. - act type #1 (set angle==move)
+extern Task gong_move_task;
+int set_angle = 50;
+void gong_move() {
+  //
+  MONITORING_SERIAL.print("gong_move go -> ");
+  MONITORING_SERIAL.print(set_angle);
+  MONITORING_SERIAL.println(" deg.");
+  //
+  servo.attach(D6);
+  servo.write(set_angle);
+  servo_release_task.restartDelayed(100);
+}
+Task gong_move_task(0, TASK_ONCE, &gong_move);
+//*-*-*-*-*-*-*-*-*-*-*-*-*
+
+//
+extern Task hello_task;
+static int hello_delay = 0;
+void hello() {
+  //
+  byte mac[6];
+  WiFi.macAddress(mac);
+  uint32_t mac32 = (((((mac[2] << 8) + mac[3]) << 8) + mac[4]) << 8) + mac[5];
+  //
+  Hello hello(String(MY_SIGN), MY_ID, mac32); // the most basic 'hello'
+  // and you can append some floats
+  static int count = 0;
+  count++;
+  hello.h1 = (count % 1000);
+  hello.h2 = set_angle;
+  // hello.h3 = 0;
+  // hello.h4 = 0;
+  //
+  uint8_t frm_size = sizeof(Hello) + 2;
+  uint8_t frm[frm_size];
+  frm[0] = '{';
+  memcpy(frm + 1, (uint8_t *) &hello, sizeof(Hello));
+  frm[frm_size - 1] = '}';
+  //
+  esp_now_send(NULL, frm, frm_size); // to all peers in the list.
+  //
+  MONITORING_SERIAL.write(frm, frm_size);
+  MONITORING_SERIAL.println(" ==(esp_now_send/0)==> ");
+  //
+  if (hello_delay > 0) {
+    if (hello_delay < 100) hello_delay = 100;
+    hello_task.restartDelayed(hello_delay);
+  }
+}
+Task hello_task(0, TASK_ONCE, &hello, &runner, false);
+
+//task #0 : blink led
+extern Task blink_task;
+void blink() {
+  //
+  static int count = 0;
+  count++;
+  //
+  switch (count % 4) {
+  case 0:
+    digitalWrite(LED_PIN, LOW); // first ON
+    blink_task.delay(LED_ONTIME);
+    break;
+  case 1:
+    digitalWrite(LED_PIN, HIGH); // first OFF
+    blink_task.delay(LED_GAPTIME);
+    break;
+  case 2:
+    digitalWrite(LED_PIN, LOW); // second ON
+    blink_task.delay(LED_ONTIME);
+    break;
+  case 3:
+    digitalWrite(LED_PIN, HIGH); // second OFF
+    blink_task.delay(LED_PERIOD - 2* LED_ONTIME - LED_GAPTIME);
+    break;
+  }
+}
+Task blink_task(0, TASK_FOREVER, &blink, &runner, true); // -> ENABLED, at start-up.
+
+// on 'Note'
+void onNoteHandler(Note & n) {
+  //
+  if (n.id == MY_GROUP_ID || n.id == MY_ID) {
+    //
+    if (n.pitch == GONG_MOVE_KEY && n.onoff == 1) {
+      set_angle = n.x3;
+      //
+      if (set_angle < 0) set_angle = 0;
+      if (set_angle > 180) set_angle = 180;
+      //
+      gong_move_task.restartDelayed(10);
+      //
+    }
+  }
+}
+
+// on 'receive'
+void onDataReceive(uint8_t * mac, uint8_t *incomingData, uint8_t len) {
+
+  //
+  //MONITORING_SERIAL.write(incomingData, len);
+
+  //
+#if defined(HAVE_CLIENT)
+  Serial.write(incomingData, len); // we pass it over to the client.
+#endif
+
+  // open => identify => use.
+  if (incomingData[0] == '{' && incomingData[len - 1] == '}' && len == (sizeof(Hello) + 2)) {
+    Hello hello("");
+    memcpy((uint8_t *) &hello, incomingData + 1, sizeof(Hello));
+    //
+    MONITORING_SERIAL.println(hello.to_string());
+    //
+  }
+
+  // open => identify => use.
+  if (incomingData[0] == '[' && incomingData[len - 1] == ']' && len == (sizeof(Note) + 2)) {
+    Note note;
+    memcpy((uint8_t *) &note, incomingData + 1, sizeof(Note));
+    onNoteHandler(note);
+
+    //is it for me?
+    if (note.id == MY_GROUP_ID || note.id == MY_ID) {
+      hello_delay = note.ps;
+      if (hello_delay > 0 && hello_task.isEnabled() == false) {
+        hello_task.restart();
+      }
+    }
+
+    MONITORING_SERIAL.println(note.to_string());
+  }
+}
+
+// on 'sent'
+void onDataSent(uint8_t *mac_addr, uint8_t sendStatus) {
+  if (sendStatus != 0) MONITORING_SERIAL.println("Delivery failed!");
+}
+
+//
+void setup() {
+
+  //led
+  pinMode(LED_PIN, OUTPUT);
+
+  //serial
+  Serial.begin(115200);
+  delay(100);
+
+  //info
+  Serial.println();
+  Serial.println();
+  Serial.println("\"hi, i m your postman.\"");
+  Serial.println("-");
+  Serial.println("- my id: " + String(MY_ID) + ", gid: " + String(MY_GROUP_ID) + ", call me ==> \"" + String(MY_SIGN) + "\"");
+  Serial.println("- mac address: " + WiFi.macAddress() + ", channel: " + String(WIFI_CHANNEL));
+#if defined(HAVE_CLIENT)
+  Serial.println("- ======== 'HAVE_CLIENT' ========");
+#endif
+#if defined(SERIAL_SWAP)
+  Serial.println("- ======== 'SERIAL_SWAP' ========");
+#endif
+#if defined(DISABLE_AP)
+  Serial.println("- ======== 'DISABLE_AP' ========");
+#endif
+#if defined(HAVE_CLIENT_I2C)
+  Serial.println("- ======== 'HAVE_CLIENT_I2C' ========");
+#endif
+  Serial.println("-");
+
+  //wifi
+  WiFiMode_t node_type = WIFI_AP_STA;
+#if defined(DISABLE_AP)
+  system_phy_set_max_tpw(0);
+  node_type = WIFI_STA;
+#endif
+  WiFi.mode(node_type);
+
+  //esp-now
+  if (esp_now_init() != 0) {
+    Serial.println("Error initializing ESP-NOW");
+    return;
+  }
+  esp_now_set_self_role(ESP_NOW_ROLE_COMBO);
+  esp_now_register_send_cb(onDataSent);
+  esp_now_register_recv_cb(onDataReceive);
+  //
+  Serial.println("- ! (esp_now_add_peer) ==> add a 'broadcast peer' (FF:FF:FF:FF:FF:FF).");
+  uint8_t broadcastmac[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
+  esp_now_add_peer(broadcastmac, ESP_NOW_ROLE_COMBO, 1, NULL, 0);
+
+  //
+  Serial.println("-");
+  Serial.println("\".-.-.-. :)\"");
+  Serial.println();
+
+#if defined(SERIAL_SWAP)
+  Serial.println("-      ======== 'SERIAL_SWAP' ========");
+  // a proper say goodbye.
+  Serial.println("\"bye, i will do 'swap' in 1 second. find me on alternative pins!\"");
+  Serial.println("\"    hint: osc wiring ==> esp8266(serial.swap) <-> teensy(serial3)\"");
+  Serial.println("-");
+  Serial.println("\".-.-.-. :)\"");
+  delay(1000);   // flush out unsent serial messages.
+
+  // moving...
+  Serial.swap(); // use RXD2/TXD2 pins, afterwards.
+  delay(100);    // wait re-initialization of the 'Serial'
+#endif
+
+  //random seed
+  randomSeed(analogRead(0));
+
+  //tasks
+  runner.addTask(gong_move_task);
+  runner.addTask(servo_release_task);
+}
+
+void loop() {
+  //
+  runner.execute();
+  //
+}