Comments on: ESP-NOW with ESP32: Send Data to Multiple Boards (one-to-many)

By: Sara Santos

Sara Santos — Wed, 30 Jul 2025 15:51:47 +0000

In reply to Mike.

Hi.
What code exactly is giving you problems?

Regards,
Sara

By: Mike

Mike — Mon, 28 Jul 2025 10:44:05 +0000

Hi, thanks for all the tutorials! I’m beginning to work through the ESP32-now material.

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

By: Michael

Michael — Thu, 12 Jun 2025 19:34:12 +0000

Thank you! Downgrading the board installation solved my problem.
Kind Regards,
Michael

By: Sara Santos

Sara Santos — Tue, 10 Jun 2025 21:34:02 +0000

In reply to Michael.

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

By: Michael

Michael — Mon, 09 Jun 2025 22:27:43 +0000

Hi Rui and Sara,
Thank you for your excellent tutorials. I have been using ESP_NOW for several months successfully. This week the code no longer compiles on Arduino IDE.
I tried copying and compiling your sender example and received the same error:
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]

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

By: Pierre-Yves MULLER

Pierre-Yves MULLER — Thu, 13 Jun 2024 11:21:00 +0000

Hi,
I try your code (one ESP32 sender and 3 ESP8266 receiver) and it works fine ! Thank you.
But when I extend with 6 ESP8266 receiver I noticed on the Arduino IDE Serial Monitor of the ESP32 sender sent only 4 or sometime 5 “Delivery Success” message!
It looks like a timing jam… Do you have an idea why.
I would like to send data to 20 receivers IN THE SAME TIME! Can you provide me any help ?
Thank’s

By: ADAM SZCZUROWSKI

ADAM SZCZUROWSKI — Thu, 23 May 2024 15:39:05 +0000

Hi Sara.
I try to send data from One ESP32 Board to two ESP32
Exactly with your code. The problem is it sends data only for few meters distance.
In longer distance (~20m) I’m getting msg “Delivery Fail”
I use DEVKIT V1.
Could you tell me why?

By: whispers

whispers — Mon, 04 Dec 2023 00:16:19 +0000

Great tutorial.. Is it possible to add “auto-peer” stuff to this? Or do you need to connect to a real/live ‘network’ (username/password required) to do such a thing?

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!

By: LaZorraTech

LaZorraTech — Thu, 28 Sep 2023 18:36:16 +0000

In reply to Saffanah Putri. I've had issues sending to multiple boards if I am sending the messages one immediately after the other. It seems like the second message doesn't get transmitted as it is still dealing with the first. Have you tried adding a delay between sending messages?

By: Saffanah Putri

Saffanah Putri — Fri, 22 Sep 2023 08:51:45 +0000

In reply to Felipe Paulino. Hi Felipe, do you have discover the solution yet of this problem? I had the same problem as well.