Add enhanced advertising examples

[polldo]

While the old way of preparing advertising data is still supported, an alternative enhanced method to build advertising packets is now available.
It consists in defining and configuring an object of type 'BLEAdvertisingData' to build the desired packet.
When it has been configured, by setting the appropriate parameters, it can be used to populate the advertising data packet or the scan response data packet.
Following this way, the user can decide in which packet each parameter should be put.
Also, it is now possible to configure an advertising packet (advertising or scan response) by passing a raw data packet.
If an advertising packet has a raw data parameter set, all its other parameters will be ignored.

Also, advertising parameters such as manufacturer data, service data or raw data should have a GLOBAL scope, because they are passed as pointers and are not copied internally.

Example EnhancedAdvertising.ino shows how to build generic advertising and scan response packets.
Example RawDataAdvertising.ino shows how to configure an advertising packet given an already encoded raw advertising packet

[sebromero]

@polldo Interesting. Does it affect the performance? If so, how?

[polldo]

Hi @sebromero
There should't be any critical performance penalty, however it is required slightly more CPU work to perform:

• some checks more when building the actual advertising packet plus some extra memcpy of very few bytes
• some checks more when setting its parameters

The aspect I'm mostly concerned about in terms of performance is that each time the BLE.advertise() function is called, the advertising packets (advertising data and scan response data) are always rebuilt (i.e. their paramaters are encoded) even if their parameters did not change at all. (However, this was the original behaviour, even before this PR)
To handle this, it could be added a flag indicating whether or not any of the advertising data parameters have been changed.

[gmacario]

Hello,

That's an interesting concept but I see no updates for a long time.

Is the PR ready to be merged? If not, what is still missing?

[facchinm]

@manchoz @giulcioffi can we merge it?

[manchoz]

@facchinm LGTM. Tested working.

[per1234]

@Nasrino17 this is not an appropriate place to request assistance. If you want help, make a topic on Arduino Forum:

https://forum.arduino.cc/

I'm sure we'll be able to help you solve the problem over there.