Bootloader, iOS and secure connection

RE: Bootloader, iOS and secure connection

Hung Bui — Wed, 18 Mar 2015 11:52:17 GMT

Good that you found the root cause. You are welcome to select the answer as correct and the case can be closed.

RE: Bootloader, iOS and secure connection

Marcel Mulder — Tue, 17 Mar 2015 15:45:34 GMT

I did some more testing and it is faulty behavior of LightBlue. Sorry for the confusion.

RE: Bootloader, iOS and secure connection

Marcel Mulder — Tue, 17 Mar 2015 15:38:24 GMT

What I meant was you may not change the ATT table when in the middle of a connection connection, as you also mentioned. The result is that you have to reconnect to perform a change. Or do I miss something?

RE: Bootloader, iOS and secure connection

Marcel Mulder — Tue, 17 Mar 2015 15:30:18 GMT

It looks like this is the behavior of LightBlue (which I use for testing). It behaves different in iOS 8.1 and in iOS 8.2. I get a popup saying: Connection Alert; The peripheral disconnected while being interrogated.

note: I only use encrypted links

RE: Bootloader, iOS and secure connection

Hung Bui — Tue, 17 Mar 2015 15:23:59 GMT

I haven't seen that behaviour. What I observed is that if prior to the SC indication the iOS device has already done a service discovery, it will not do a re-discovery. So it's true that service changed indication should be used when the attribute table is changed compare to the last time it is connected to the same master, not if the table is change in the middle of the connection.

I haven't seen in the spec that mentions the master should terminate and reconnect when receiving SC indication. If you can send me an example showing that iOS' behaviour it would be great.

RE: Bootloader, iOS and secure connection

Marcel Mulder — Tue, 17 Mar 2015 14:44:22 GMT

I can't sniff because it (both Master Control Panel and sniffer) does not work in a VirtualBox :-( My setup is different from yours. But when I detect in the application that the bootloader service was used I send a service changed so the iPhone does a new discovery. This works all well but when the iPhone receives the service changed it disconnects. The application however disconnect after a timeout. I think this is "normal" behavior because the specification says that the new characteristics are only valid after a reconnect.

RE: Bootloader, iOS and secure connection

Hung Bui — Tue, 17 Mar 2015 14:31:13 GMT

No, I don't. Could you capture a sniffer trace and send me ?

Note: we only send service changed when the link is encrypted. So if you haven't bonded with the device before you shouldn't receive any service changed indication.

RE: Bootloader, iOS and secure connection

Marcel Mulder — Tue, 17 Mar 2015 14:03:06 GMT

The update works as you say, but when starting the updated app the first time the iPhone with iOS 8.2 disconnects. Because of the service changed indication. You don't see that?

RE: Bootloader, iOS and secure connection

Hung Bui — Tue, 17 Mar 2015 13:23:53 GMT

I just tested again, worked smoothly. I attached the application and the bootloader hex file I used. Tested with S110 v8.0 and nRFToolbox App, Ipad iOS8.2

bootloader.hex

HRM_DFU_BONDED_S110v80.zip

RE: Bootloader, iOS and secure connection

Hung Bui — Tue, 17 Mar 2015 13:22:00 GMT

I post the next comment as an answer because I want to attach a file.

RE: Bootloader, iOS and secure connection

Marcel Mulder — Tue, 17 Mar 2015 13:02:13 GMT

There is some difference in behavior. iOS 8.2 disconnects directly after receiving a service changed. iOS 8.1.x does not.

RE: Bootloader, iOS and secure connection

Hung Bui — Tue, 17 Mar 2015 12:31:40 GMT

@Marcel: No, I guess it was 8.1.x. I can see the update to 8.2 available on my iPad now.

RE: Bootloader, iOS and secure connection

Marcel Mulder — Tue, 17 Mar 2015 08:10:19 GMT

Did you also tried this with iOS version 8.2?

RE: Bootloader, iOS and secure connection

Hung Bui — Thu, 12 Mar 2015 14:50:55 GMT

@Marcel: The main point is to have iOS to do a service discovery when we switch to bootloader. The reason why it worked when there is no bonding is that iOS will do service discovery everytime it connect to a unbonded device (if there is a service changed characteristic on it). I just tried here with SDK v8.0 DFU example and it worked pretty smooth on iOS. I modified so that the hrm dfu example require bonding. And I just have to click Upload on nRFToolbox to have the app write 0x01 to DFU control point, switch to DFU bootloader, send service changed indication, have iOS do service discovery, and then upload the new image, everything was done when the link was encrypted. I would suggest you to try with new SDK example and can record a sniffer trace and see what happens when switching to DFU when bonded.

RE: Bootloader, iOS and secure connection

Marcel Mulder — Wed, 11 Mar 2015 16:04:14 GMT

Yes I have set gatts_enable_params.service_changed to 1 in both cases. So I send a sd_ble_gatts_service_changed when I change from application to bootloader and I send a sd_ble_gatts_service_changed from bootloader to application when an update is succeeded. I really do not understand why a unsecure connection works and a secure connection not. My guess is it is a iOS problem, but I am nt completely sure.

RE: Bootloader, iOS and secure connection

Hung Bui — Wed, 11 Mar 2015 14:58:02 GMT

@Marcel: Have you make sure you set IS_SRVC_CHANGED_CHARACT_PRESENT = 1 in both the application code and the bootloader code ? The observation I had with iOS is that when you sent service changed indication and disconnect, the next time when connected, iOS device will do a service discovery and update the server attribute table.

RE: Bootloader, iOS and secure connection

Marcel Mulder — Wed, 11 Mar 2015 07:13:21 GMT

I found a work-a-round for my problem. I made the handles equal by putting the dfu service first in the initialization of the services as it is in the bootloader. This is however not done in the examples. As it actually should be.
But I am still curious if somebody else as a working setup with iOS 8, secure connection and DFU.