Hi.

For ESP32 core version before 3.3.0:
void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {

For the latest ESP32 core version 3.3.0:
void OnDataSent(const wifi_tx_info_t *mac_addr, esp_now_send_status_t status) {

So, either downgrade the ESP32 core to the previous version or use the previous line that I shared.

We’re still waiting to see if there are more breaking changes in the new core before updating all our esp-now guides.

Regards,
Sara

Hello Sara, my Name is Mike. I have the same Problem.

This is your example code:

/*********
Rui Santos & Sara Santos – Random Nerd Tutorials
Complete project details at https://RandomNerdTutorials.com/esp-now-one-to-many-esp32-esp8266/
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files.
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
*********/
#include <esp_now.h>
#include <WiFi.h>

// REPLACE WITH YOUR ESP RECEIVER’S MAC ADDRESS
uint8_t broadcastAddress1[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
uint8_t broadcastAddress2[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
uint8_t broadcastAddress3[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};

typedef struct test_struct {
int x;
int y;
} test_struct;

test_struct test;

esp_now_peer_info_t peerInfo;

// callback when data is sent
void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {
char macStr[18];
Serial.print(“Packet to: “);
// Copies the sender mac address to a string
snprintf(macStr, sizeof(macStr), “%02x:%02x:%02x:%02x:%02x:%02x”,
mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);
Serial.print(macStr);
Serial.print(” send status:\t”);
Serial.println(status == ESP_NOW_SEND_SUCCESS ? “Delivery Success” : “Delivery Fail”);
}

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_send_cb(OnDataSent);

// register peer
peerInfo.channel = 0;
peerInfo.encrypt = false;
// register first peer
memcpy(peerInfo.peer_addr, broadcastAddress1, 6);
if (esp_now_add_peer(&peerInfo) != ESP_OK){
Serial.println(“Failed to add peer”);
return;
}
// register second peer
memcpy(peerInfo.peer_addr, broadcastAddress2, 6);
if (esp_now_add_peer(&peerInfo) != ESP_OK){
Serial.println(“Failed to add peer”);
return;
}
/// register third peer
memcpy(peerInfo.peer_addr, broadcastAddress3, 6);
if (esp_now_add_peer(&peerInfo) != ESP_OK){
Serial.println(“Failed to add peer”);
return;
}
}

void loop() {
test.x = random(0,20);
test.y = random(0,20);

esp_err_t result = esp_now_send(0, (uint8_t *) &test, sizeof(test_struct));

if (result == ESP_OK) {
Serial.println(“Sent with success”);
}
else {
Serial.println(“Error sending the data”);
}
delay(2000);
}

The Error is:

Compilation error: invalid conversion from ‘void ()(const uint8_t, esp_now_send_status_t)’ {aka ‘void ()(const unsigned char, esp_now_send_status_t)’} to ‘esp_now_send_cb_t’ {aka ‘void ()(const wifi_tx_info_t, esp_now_send_status_t)’} [-fpermissive]

Hi.
What code exactly is giving you problems?

Regards,
Sara

I’ve added a line to the Getting the boards base MAC address where the MAC address is printed; I assume most users will copy the serial port output and paste into some code.
if (ret == ESP_OK) {
Serial.printf(“%02x:%02x:%02x:%02x:%02x:%02x and for C++ code “,
baseMac[0], baseMac[1], baseMac[2],
baseMac[3], baseMac[4], baseMac[5]);
Serial.printf(“{0x%02X,0x%02X,0x%02X,0x%02X,0x%02X,0x%02X}\n”,
baseMac[0], baseMac[1], baseMac[2],
baseMac[3], baseMac[4], baseMac[5]);
} else // etc

Since Espressif moved from boards version 3.2.1 to 3.3 the API for registering callbacks has changed. The compile errors seem to be about the callback definition; but my C++ coding knowledge is insufficient to disentangle the problem.
No doubt Espressif will release versions 3.3.1 etc. Can you help to update your examples to work with the 3.3.x API?

Many thanks

Hi.
I’ll try it out again.
Meanwhile, try downgrading your ESP32 boards installations. Go to Tools > Boards > Boards Manager > Search for ESP32 and try previous versions.

Regards,
Sara

I assume there has been a change in a library somewhere. Can you help?
KInd Regards,
Michael

Close to this tutorial:
https://randomnerdtutorials.com/esp-now-auto-pairing-esp32-esp8266/

but I dont need any ‘server’
no connect to a wifi/ssid (name/password)..etc (all just local ESP32 devices)

Q: Or do you -have- to connect to a network (name/password) to actually do the auto-pairing stuff in the other tutorial? (I liked everything but dont need server stuff..and no outside network connection…everything local to ESP32 boards) Adding the ‘peers’ to a list was nice so you can loop through or randomly pick one..etc.

In this tutorial.. only thing I dont understand yet is how to dynamically grab these ‘peers’ addresses… and build a list dynamically?

THANKS!