#include #include void onReceive(const uint8_t *mac_addr, const uint8_t *data, int data_len) { char message[data_len + 1]; memcpy(message, data, data_len); message[data_len] = '\0'; Serial.print("Message received: "); Serial.println(message); } void setup() { Serial.begin(115200); WiFi.mode(WIFI_STA); if (esp_now_init() != ESP_OK) { Serial.println("Error initializing ESP-NOW"); return; } esp_now_register_recv_cb(onReceive); } void loop() { // Nothing to do here, everything is handled in the callback }