LP-CC2652RSIP: Scan d'ont find all Advertising

Hi,

I have a few questions that will help us resolve this as efficiently as possible. Could you specify the SDK version you are using? Are your central and peripheral projects based on simple_central and simple_peripheral? If so, then can you specify which modifications you have made to these projects?

You mentioned that you do not get the GAP_EVT_ADV_REPORT event with your peripheral address.  Are you able to see any advertisements at all during your scans? Typically, your advertising interval and window should be twice as much as your advertising interval. If you set your scan interval and scan window to at least 20 seconds is the behavior still present? Can you try setting the advertising interval to something much smaller along with the scan window/interval to verify if the behavior is still present then? Can you try configuring your central device to scan indefinitely and share if the behavior is still observed?

I would recommend referencing the Scanning and Advertising SimpleLink Academy lab to learn more about scanning and advertising. I would also recommend referencing the Generic Access Profile (GAP) chapter of the User's Guide.

Best Regards,

Jan

Hi,

I use the SDK simplelink_cc13x2_26x2_sdk with version V5_20_00_52.

Are your central and peripheral projects based on simple_central and simple_peripheral? Yes, I have only change the ADV frequence  and scanner configuration.

Are you able to see any advertisements at all during your scans? I see some ADV during my scan, not all i see with with packetSniffer.

 If you set your scan interval and scan window to at least 20 seconds is the behavior still present? This configuration is not available, GapScan_setPhyParams fonction returns invalid range (maximum range authorized is 10.125ms)

Can you try setting the advertising interval to something much smaller along with the scan window/interval to verify if the behavior is still present then? With ADV set to 5s and scan Windows/interval set to 5.1s, My scan get the ADV after 4/5 scan request.

Can you try configuring your central device to scan indefinitely and share if the behavior is still observed? With ADV set to 10s and Scan indefinitely, I d'ont scan my ADV after 5 minutes.

Hey Florian,

I don't see an issue with the configuration you mentioned. However, if your peripheral advertises once every 10 seconds, you really do not leave too much room with regards to capturing said event. Put simply, the more advertisements that your peripheral submits, the greater the chance the scanner finds the advertisement. At the radio level, keep in mind the scanner must hop on each channel and the timing needs to perfectly align for the advertisement to be received.

You might have better luck increasing the frequency the peripheral advertises. I'm not sure I see a bug here. As Jan mentioned, you are probably better off reducing the scan window and scan in short bursts rather than using longer periods.

Hi,

I am sorry but it isn't normal that a sniffer captures all advertisements and the scanner doesn't capture one when a scan windows greather than the advertiser period. 

Can you explain to me why the scanner captures all the time my advertisement when it is in an environnement undisturbed and not capture onces when the environnement is disturbed wityh the same doncfiguration.

Is it possbile that reception buffers are full by advertisements faster and so my slow advertisement is not received ? In this case, is it posible to inscrease buffer size ?

In a Scan windows is there a limit of advertisements received ?

Hey Florian,

I apologize for my delayed reply.

Florian DAMIRON said:

Can you explain to me why the scanner captures all the time my advertisement when it is in an environnement undisturbed and not capture onces when the environnement is disturbed wityh the same doncfiguration.

Here are my thoughts on this. I assume in this case, "scanner" refers to the simple central device and not packet sniffer. In a disturbed environment with multiple advertisements, the scanner will spend time processing each received advertisement. This overhead could explain why not all advertisements are received.

Florian DAMIRON said:

In a Scan windows is there a limit of advertisements received ?

Here's an excerpt from our User's Guide:

"The maximum amount of scan responses that can be discovered during one scan can be set with the DEFAULT_MAX_SCAN_RES parameter that is passed into the maxNumReport parameter of GapScan_enable()."

Source: https://software-dl.ti.com/simplelink/esd/simplelink_cc13xx_cc26xx_sdk/6.10.00.29/exports/docs/ble5stack/ble_user_guide/html/ble-stack-5.x/gap-cc13xx_cc26xx.html#gap-scanner 

If maxNumReport is 0 (for unlimited scanning), then the application is in charge of maintaining its own scan results list. This is done as an example in the default simple_central when DEFAULT_DEV_DISC_BY_SVC_UUID is set to true. You can see the "scanList" parameter. Note that this buffer is still governed by the same define DEFAULT_MAX_SCAN_RES, but this can be changed depending on your application. The device should be receiving the SC_EVT_ADV_REPORT for each received advertisement. If you are not receiving this with your event, then the advertisement has not yet been received.