Re: Advertising and scanning states in Bluetooth Low-Energy
Re: Advertising and scanning states in Bluetooth Low-Energy
- Subject: Re: Advertising and scanning states in Bluetooth Low-Energy
- From: pietro gonizzi <email@hidden>
- Date: Tue, 14 Feb 2012 12:43:01 +0100
Hi Joakim,
thanks for replying.
For instance, if you use Advertising Interval=20 ms, then the time between two consecutive PDUs should be at least less than 20/3=6.66 ms. Is this correct?
| No, the advertising PDUs can be clustered. Meaning, you can send them back to back at the beginning of the event.
So, if you send 3 PDUs back to back on 3 different channels (37, 38, and 39, respectively) you then have to synchronize the receiver to these channels to listen to a response PDU. For instance, let's suppose that the advertising PDU is of type ADV_IND and the response PDU is either of type SCAN_REQ or CONNECT_REQ. How do you know the exact time interval you have to listen to each channel? You then have to do channel switching, isn't it?
Pietro
Il giorno 13 febbraio 2012 20:42, Joakim Linde
<email@hidden> ha scritto:
Hi Pietro,
See comments below.
Thanks,
Joakim
On Feb 13, 2012, at 9:46 AM, pietro gonizzi wrote:
Hi all,
in the Core Specification 4.0 for Bluetooth Low Energy, devices entering the Scanning State shall listen on an advertising channel index (37, 38, or 39, respectively) for the duration of the scanWindow parameter. Then, the scanInterval parameter is defined as the interval between the start of two consecutive scan windows. Both parameters should be less than or equal to 10.24 s, with scanWindow less than or equal to the scanInterval.
Are there any default values used for these parameters? Is it possible to configure the scanWindow parameter from the host?
The Core Bluetooth framework does not provide a method for changing the scan interval or scan window. The OS selects an interval and window considering performance and power consumption. In iOS, more scanning is performed when the App is in the foreground and reduced when the App goes in the background.
We have tried to design the algorithm so it works in most use case scenarios. As always, we are interested in feedback so if you experience any issues, please let us know.
Regarding the Advertising State, the BluetoothDesignGuidelines indicates an Advertising Interval parameter of 20 ms for at least 30 seconds. Within this interval, an advertising event shall transmit an advertising PDU at each of the 3 advertising channels. The specification says that the time between the beginning of two consecutive PDUs within an advertising event shall be less than or equal to 10ms. How is this time computed?
Normally, distance is calculated beginning of packet to beginning of packet.
Which value is used for that?
The distance between advertising PDUs within an advertising event is implementation depended.
Does it depend on the value of the Advertising Interval parameter?
No, it does not.
For instance, if you use Advertising Interval=20 ms, then the time between two consecutive PDUs should be at least less than 20/3=6.66 ms. Is this correct?
No, the advertising PDUs can be clustered. Meaning, you can send them back to back at the beginning of the event.
Any help would be appreciated.
Regards,
Pietro Gonizzi
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Bluetooth-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden