BLE client with up to 100 PAIRED devices

[luigino55]

Hello!

A possible great customer requests us to develop an application where: some devices are activated upon connection with up to 100 BLE keys. 100 BLE Paired devices

The BLE security level must be MODE 1, LEVEL 3 or 4  (they ask)

Beyond these requirements, naturally arises firmware upgrade OTA 

So my main questions at the moment are:

1. a) Can Nordic stack handle “MODE 1, LEVEL 3 or 4” security?
2. b) Can we get up to 100 BLE Paired devices? (or what's the max)
3. c) Will Bootloader allow complete Fw upgrade?
4. d) Can Nordic support us with some starting designs ?

 

Waiting your kind reply

Luigi, Italy

[haakonsh]

1. Yes, see Peer Manager. 
   
   
2. There's no predefined maximum limit in the Peer Manager, but there is a practical limit as each bond requires ~100 bytes of persistent storage. That means that you will have to reserve at least  ~10kB of flash for the bonds. 
   We have not tested the Peer Manager for 100 bonds so you should proceed with caution. 
   
   
3. Yes, see Bootloader and DFU modules.
   
   
4. What do you need?

[luigino55]

Ok thanks for your reply!

About pint 4. I was meaning one (or more) Nordic nRF... Project suited to start my application.

Please notice that it's some yaers we're working with Cypress, but their stack only allows up to 4 bonden devices. So I think we need to turn to Nordic, but here we need to enter your development environment in a short period of time.....as you know the greatest difficulties are interfacing the stack properly, without wasting a lot of time.

In other words, if we get our customer order, can you support us promptly with some starting project?

If you agree, I'll send you our customer needs in detail.

Thanks a lot

Have a nice day

Luigi

[haakonsh]

We will support any customer as best we can. In 85-90% of cases, we answer within 24H, regardless of who requests the support. Though we don't work on weekends. 

I suggest the customer get their hands on 2-4 nRF52840 DKs (PCA10056), and a few nRF52 dongles(PCA10059). 

The nRF52840DK has as all the features of BLE 5.1 with the exception of direction-finding, for that you need the nRF52833 or nRF52811. 

Mouser will have stock of our development kits and dongles.  

I also suggest that you get in contact with our RSM for Italy, [email protected] if you've not established a relationship yet. Our RSMs can answer many of your non-technical questions related to your project.

See nRF5 Getting Started, Product development with nRF5 Series SoCs, and 

Software development Getting Started Guides. 

[luigino55]

Ok Thanks

BR

Luigi

[luigino55]

Sorry I forgot an important question: about the same design, the customer asks a maximum time delay of 1000mS from the moment the user activates the key fob (pwr on, startup etc..)  and the remote door lock opening!

Even though I'm not experienced with Ble Pairing, I think it'll take more time.

But: do you think that in case of Bonded devices that period could be respected?

Thanks

Regards, Luigi

[haakonsh]

If the devices are bonded both devices have stored their pairing information and they will therefore not need to pair again. Pairing does take some time, but you only need to do it the first time if the devices are bonded.

Once devices are bonded you can use directed advertisements to establish a connection, this does shorten the time needed to connect. The key variable here is the Peripheral's Advertisement Interval and the Central's Scan Window and Scan Intervall. If both run at 100% duty-cycle you will likely connect in less than 50ms, but it comes at a cost of higher energy consumption. You, therefore, need to trim the Advertising Interval, Scan Interval, and Scan Window according to your needs. If your needs are ~1s delay then you set an AI, SI, and SW to values that give you a maximum delay of 1s in say 95% of your use-cases. 

Also note that you can trim AI, SI, and SW according to the given energy budgets of the two devices. If f.ex the Peripheral keyfob has a much lower energy budget than the Central lock, you can set the Advertising Interval low and Scan Interval and Scan Window high and still get the required latency.