Comments on: ESP32 CYD with ESP-NOW: Receive and Display Data From Multiple Boards

By: Bryan Staines

Bryan Staines — Tue, 29 Jul 2025 16:43:30 +0000

Hi Sara
I’m fairly new to this game so might need a bit of hand holding!
I get the following when compiling the code:

C:\Users\44784\AppData\Local\Temp.arduinoIDE-unsaved2025629-20436-411cb1.v10f6\sketch_jul29a\sketch_jul29a.ino: In function ‘void setup()’:
C:\Users\44784\AppData\Local\Temp.arduinoIDE-unsaved2025629-20436-411cb1.v10f6\sketch_jul29a\sketch_jul29a.ino:78:29: 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]
78 | esp_now_register_send_cb (OnDataSent);
| ^~~~~~~~~~
| |
| void ()(const uint8_t, esp_now_send_status_t) {aka void ()(const unsigned char, esp_now_send_status_t)}
In file included from C:\Users\44784\AppData\Local\Temp.arduinoIDE-unsaved2025629-20436-411cb1.v10f6\sketch_jul29a\sketch_jul29a.ino:7:
C:\Users\44784\AppData\Local\Arduino15\packages\esp32\tools\esp32-arduino-libs\idf-release_v5.5-b66b5448-v1\esp32/include/esp_wifi/include/esp_now.h:185:54: note: initializing argument 1 of ‘esp_err_t esp_now_register_send_cb(esp_now_send_cb_t)’
185 | esp_err_t esp_now_register_send_cb(esp_now_send_cb_t cb);
| ~~~~~~~~~~~~~~~~~~^~
exit status 1

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 have installed:
ARDUINO ESP32 BOARDS by ARDUINO v 2.0.18-arduino .5
esp32 by Espressif Systems v 3.3.0

Any help would be greatly appreciated, thank you
Bryan

By: Sara Santos

Sara Santos — Wed, 23 Jul 2025 14:15:11 +0000

In reply to Dale W Etchells.

Hi.
Thanks. I don’t know how that typo happened.
But, it’s fixed now.
Regards,
Sara

By: Sara Santos

Sara Santos — Wed, 23 Jul 2025 14:14:09 +0000

In reply to Dale W Etchells.

Great!
Thanks for your feedback.
Regards,
Sara

By: Dale W Etchells

Dale W Etchells — Tue, 22 Jul 2025 23:57:25 +0000

Just found a very small mistake in you documentation
Defining the Display Width and Height
You need to define your display width and height in all your sketches that use LVGL. If you’re using the recommended display, the size is 240×320.
Your example shows ” # define SCREEN_WIDTH as 241 and should be 240″

By: Dale W Etchells

Dale W Etchells — Tue, 22 Jul 2025 22:04:20 +0000

Hi Sara, Just letting you know that I didn’t have any issues with this guide. I like using VS Code & Platformio to build and had no issues using it. Great little build. Just a note I didn’t have to use the step to increase the memory “Go to Tools > Partition scheme > choose anything that has more than 1.4MB APP, for example: “Huge APP (3MB No OTA/1MB SPIFFS“.”

Keep up the great work.

By: Sara Santos

Sara Santos — Thu, 17 Jul 2025 14:05:18 +0000

In reply to John.

Hi.
Can you tell me the version of the ESP32 boards you have installed»
Go to Tools > Boards > Boards Manager > search for ESP32 and check the version.

Regards,
Sara

By: John

John — Thu, 17 Jul 2025 04:29:37 +0000

Hi
Having problems compiling the receiver code sing platformio, I get the following errors

src/main.cpp:68:23: error: ‘esp_now_recv_info’ does not name a type; did you mean ‘esp_now_peer_info’?
void OnDataRecv(const esp_now_recv_info recv_info, const uint8_t *incomingData, int len)
^~~~~~~~~~~~~~~~~
esp_now_peer_info
src/main.cpp: In function ‘void OnDataRecv(const int, const uint8_t*, int)’:
src/main.cpp:76:34: error: request for member ‘src_addr’ in ‘* recv_info’, which is of non-class type ‘const int’
uint8_t mac_addr = recv_info->src_addr;
^~~~~~~~
src/main.cpp: In function ‘void setup()’:
src/main.cpp:266:28: error: invalid conversion from ‘void ()(const int*, const uint8_t*, int)’ {aka ‘void ()(const int, const unsigned char*, int)’} to ‘esp_now_recv_cb_t’ {aka ‘void ()(const unsigned char, const unsigned char*, int)’} [-fpermissive]
esp_now_register_recv_cb(OnDataRecv);
^~~~~~~~~~
In file included from src/main.cpp:26:
/home/john/.platformio/packages/framework-arduinoespressif32/tools/sdk/esp32/include/esp_wifi/include/esp_now.h:136:54: note: initializing argument 1 of ‘esp_err_t esp_now_register_recv_cb(esp_now_recv_cb_t)’
esp_err_t esp_now_register_recv_cb(esp_now_recv_cb_t cb);
~~~~~~~~~~~~~~~~~~^~
*** [.pio/build/esp32doit-devkit-v1/src/main.cpp.o] Error 1

Can you help please
Regards
John

By: Sara Santos

Sara Santos — Sun, 13 Jul 2025 10:57:24 +0000

In reply to Paul.

Hi.
I haven’t tried it. But, I think so.
Regards,
Sara

By: Umar

Umar — Sun, 13 Jul 2025 04:33:34 +0000

What if dont have clear view about the pinouts of my CYD model? How to identify these pinouts. I know there are unused pins of esp32 left but there is no pinout in shape of connectors.

By: Paul

Paul — Sat, 12 Jul 2025 19:25:15 +0000

In reply to Sara Santos. Will it work on ESP32 C3 ? tanx !