[DFU] Is the peripheral doing direct advertisement at bootloader?

[MANGO]

Hi, I'm using SDK 7.2 and S110 7.1.

I haven't mirgrated to SDK 10 yet.

I'm using the HRS and bootloader (which uses dual bank and BLE OTA) example.

After I select a peripheral device, I noticed that it disconnects and the peripheral resets and runs the bootloader.

When the peripheral goes to the bootloader, it automatically pairs

(or maybe bond might be correct since this uses HRS) with my iPhone again.

My questions are,

1. Is it using direct advertising when the peripheral automatically connects to my iPhone?

If not, what is happening when they are connected again at the bootloader?

2. How does the peripheral remembers my iPhone's address?

In this case (the HRS example), the peripheral has the peer address and the IRK of my iPhone.

Since iOS device uses Random Resolvable Address,

I'm curious how the peripheral knows my iPhone has scanned ther peripheral even though its address has changed.

-Best Regards, Mango

[Vidar Berg]

Hi, the bootloader uses the dfu_ble_peer_data_t (bond sharing) received from the application to either start direct or whitelist advertising, and whitelist advertising will be used when the address type is private resovable (resolved with IRK). Note that it is the iphone app that attempts to re-connect.

[MANGO]

Thanks, what about if the peripheral uses a service that uses pairing, not bonding (like NUS)?

In this case, I think the bootloader won't use the bond sharing.

[Vidar Berg]

correct, it won't do bond sharing if only paired, but it the application can still share a static address so the bootloader can do directed advertising.

[MANGO]

Do you mean after disconnecting at the main program (like NUS example) and

jumping to the bootloader, the board also knows the address of the central

(in this case, my iPhone's resolvable address or static address) ?

This is a part about share a static address.

As far as I know, I thought iOS CoreBluetooth has many restrictions about giving the phone's address.

If so, can you tell which function / method / delegate makes it share the address?

(From the DFU functions and the DFU library)

[Vidar Berg]

In dfu_app_handler.c you can see that the address is being set with the dfu_ble_svc_peer_data_set function (SV instruction - SV call is located in bootloader). The restriction in CoreBluetooth is that the IRK is only distributed during bonding. This means you can do directed advertisement when not bonded, and whitelist or normal advertisement when bonded (privacy enabled).