Chained Advertisement

[Mihir Tailor]

Hello,

I am using PCA10040 development board based on nRF52832, Softdevice 6.1.0 & SDK 15.1.0.

On the Nordic website, I have verified that Softdevice v6.1.0 supports Chained Advertisement feature of Bluetooth 5.

But I cant perform Chained Advertising application.

So, I want to ask that does SDK 15.1.0 not having the feature of Chained Advertisement?

Thanks

[Olivier Balitch]

Hello,

I have same setup (PCA10040 deb board with nRF52832, Softdevice 6.1.0 & SDK 15.1.0). I wanted to use the extended advertisement feature to advertise more than 255 bytes of data.

Looking to the release note, Nordic claim they support chained advertisement but in ble_gap.h header file, I see  BLE_GAP_ADV_SET_DATA_SIZE_EXTENDED_MAX_SUPPORTED = 255.

The BLE specification mentions that up to 1650 bytes could be sent in an extended advertisement. Maybe Nordic supports a limited number of chained packets but then the define in ble_gap.h does not match.

@Mihir: Did you manage to do some extended advertisement with data length > 255?

@Nordic support: Can you please help?

Thanks

[run_ar]

For reference: https://devzone.nordicsemi.com/f/nordic-q-a/38702/maximum-extended-advertising-data-length-supported

[Mihir Tailor]

Hi Olivier....
I think you are talking about the following lines under the section 2.3.4.9 Host Advertising Data
The total amount of Host Advertising Data before fragmentation shall not exceed 1650 octets.
You may be misunderstood this line.
Actually BLE stack is divided into two parts: 1. Host and 2. Controller
Here, Host Advertising Data means the Data sending from the Host to the Controller
So, before the fragmentation by the link layer, the maximum data size sent by the Host to the Controller is 1650 octets.

So, Link Layer receives the Maximum Host Advertising Data of 1650 Bytes at a time.
But Link Layer can send only 255 bytes of Advertisement Data in single packet. So it can fragment the Data received from the Host if Received Data is greater than 255 Bytes.

Other point that I want to mention is that the size of bytes that Host can send to the Controller is greater than 1650 than L2CAP Layer in the Host fragments that data and send the only maximum size of 1650 bytes to the Controller.

I hope this explanation helps you to solve your query.

Have a Nice Day...

[Mihir Tailor]

This link help you to understand further.

Kindly see Extended Advertisements Section in this link

https://blog.nordicsemi.com/getconnected/bluetooth-5-advertising-extensions

[Olivier Balitch]

Hi Mihir,

Thanks for your answer. I got the answer on another thread:

https://devzone.nordicsemi.com/f/nordic-q-a/38702/maximum-extended-advertising-data-length-supported

Nordic confirmed that the maximum advertising data length from host to link layer is 255 bytes. Their advertising chain can contain up to 255 bytes.

Best regards,

Olivier