ESPNOW_ESP32 Receiver Example from https://www.youtube.com/watch?v=Ydi0M3Xd_vs

slim-owl-rx.ino

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

#define CHANNEL 1

uint8_t newData;

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

  WiFi.mode(WIFI_AP);
  WiFi.softAP("RX_1", "RX_1_Password", CHANNEL, 0);

  esp_now_init();
  esp_now_register_recv_cb(OnDataRecv);
}

void loop(){
  Serial.print("I did this to data -> ");
  Serial.println(newData * 5);
  delay(3000);
}

/** callback when data is recv from Master **/
void OnDataRecv(const uint8_t *mac_addr, const uint8_t *data, int data_len)
{
  Serial.print("I just received -> ");
  Serial.println(*data);
  memcpy(&newData, data, sizeof(newData));
}