ESP32 Forum

Posted: **Sat Apr 04, 2026 2:20 pm**

Hello,
I'm not sure if I'm posting this in the right place, but I'm having a problem with the esp_now v2.0 program. My data is being truncated when my buffer is set to

CONFIG_ESPNOW_SEND_LEN=1024

.

I used the espnow example, and instead of using the

esp_fill_random

function to fill the buffer, I filled it with '%'.

In Wireshark, I see my buffer data truncated by 240 entries. I end up with 1014 entries in total.

It might be an option or parameter I've missed, but I'm stuck on this problem.

Thank you for any help you can provide.

Sincerely, Marc.

PS : I am using idf.py 6.0

Posted: **Sun Apr 05, 2026 12:57 am**

This structure will be used.
https://github.com/espressif/esp-idf/bl ... mple.h#L67

CONFIG_ESPNOW_SEND_LEN=1024

This represents the overall size of the structure.
The size of the payload within the structure is 1014 bytes.

Code: Select all

// send_param->len = CONFIG_ESPNOW_SEND_LEN(1024)
// sizeof(example_espnow_data_t) = 10
esp_fill_random(buf->payload, send_param->len - sizeof(example_espnow_data_t));

Posted: **Sun Apr 05, 2026 4:21 am**

Hello,
I more or less understood that.

How can you explain that Wireshark is telling me the data is truncated?

Thank you for the information.

Regards, Marc.

Posted: **Sun Apr 05, 2026 8:59 am**

Hello,

I'm wondering if the data sent by esp_now, specifically the "Data: IEEE80211_vendorspecific" parameter, complies with the standard, which may have changed?

Or perhaps the Wireshark program is reporting truncated data even though the "Data" parameter is 231, or even 121.

I don't want to overlook this parameter, but I'm having trouble understanding it.

Thank you for any help.

Sincerely, Marc.

Posted: **Fri Apr 17, 2026 8:11 am**

Here is format of ESPNOW.

https://docs.espressif.com/projects/esp ... ame-format

Category Code: 0x7f
Organization Identifier: 0x18 0xfe 0x34
Random Value: 0x4c 0x8c 0x80 0x96
Vendor Specific Content:0xdd 0x73 0x18 0xfe 0x34 0x04 0x02 0x00 0x00 0x05 0x00 0x08 0x00 0x4f 0x4f 0x4f 0x4f 0x25 0x25 -----------------------
- Element ID:0xdd
- Length 0x73
- Organization Identifier:0x18 0xfe 0c34
- Type:0x04
- More data:0x0
- Version: 0x02
- Body:0x00 0x00 0x05 0x00 0x08 0x00 0x4f 0x4f 0x4f 0x4f 0x25 0x25 -----------------------

Maybe, IEEE 802.11 does not specify the format of the data following the organization identifier.
Therefore, Wireshark cannot accurately understand this part.

Posted: **Fri Apr 17, 2026 8:26 am**

Hello,
I completely agree. In fact, the first segmentation is done on 240 data points, then on 250 data points, not counting the 7 control data points.

I've adapted the PC program accordingly.

Thank you.
Sincerely, Marc.

ESP32 Forum

esp_now v2 data truncated.

esp_now v2 data truncated.

Re: esp_now v2 data truncated.

Re: esp_now v2 data truncated.

Re: esp_now v2 data truncated.

Re: esp_now v2 data truncated.

Re: esp_now v2 data truncated.