Sample: ESP-NOW broadcast

sender.cpp

// ESP-NOW broadcast sender

#include <Arduino.h>
#include <esp_now.h>
#include <WiFi.h>

// タクトスイッチのピン
constexpr uint8_t SW_PIN = G39;
constexpr uint8_t CHANNEL = 1;
constexpr uint8_t BROADCAST[] = {
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};

void sendCallback(const uint8_t *mac_addr, esp_now_send_status_t status) {
  Serial.printf("sent: peer=%02X:%02X:%02X:%02X:%02X:%02X, status=%d\r\n",
      mac_addr[0], mac_addr[1], mac_addr[2],
      mac_addr[3], mac_addr[4], mac_addr[5],
      status);
}

void setup() {
  Serial.begin(115200);
  ::pinMode(SW_PIN, INPUT_PULLDOWN);

  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
  if (::esp_now_init() != ESP_OK) {
    // failed!
    ::esp_restart();
  }
  esp_now_peer_info_t info = {};
  ::memcpy(info.peer_addr, BROADCAST, 6);
  info.channel = CHANNEL;
  info.encrypt = false;
  if (::esp_now_add_peer(&info) != ESP_OK) {
    // failed!
    ::esp_restart();
  }
  
  // 無くても動くよ
  ::esp_now_register_send_cb(sendCallback);
}

void loop() {
  if (::digitalRead(SW_PIN) != LOW) return;

  static uint8_t v = 0;
  Serial.printf("send: value = %d\r\n", v);
  ::esp_now_send(BROADCAST, &v, 1);
  v++;

  // wait for release.
  while (::digitalRead(G39) == LOW) {
    ::delay(1);
  }
}

target.cpp

// ESP-NOW receiver

#include <Arduino.h>
#include <esp_now.h>
#include <WiFi.h>

void recvCallback(const uint8_t *mac_addr, const uint8_t *data, int data_len) {
  Serial.printf("recv: peer=%02X:%02X:%02X:%02X:%02X:%02X, data=",
      mac_addr[0], mac_addr[1], mac_addr[2],
      mac_addr[3], mac_addr[4], mac_addr[5]);
  for (auto i = 0; i < data_len; ++i) Serial.printf("%02X", data[i]);
  Serial.println();
}

void setup() {
  Serial.begin(115200);

  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
  if (::esp_now_init() != ESP_OK) {
    ::esp_restart();
  }
  ::esp_now_register_recv_cb(recvCallback);
}

void loop() {
}