Connection interval issue between nRF51822 and iOS device

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Fri, 05 Jun 2015 14:12:54 GMT

Hi Anand No we have not heard about the reason for this from Apple.

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Thu, 04 Jun 2015 10:26:56 GMT

Hi Stefan,

Any update on the 10 second connection interval between the ioS and nRF .

Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Wed, 13 May 2015 12:16:03 GMT

Thanks Stefan, I will look into that guideline.

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Wed, 13 May 2015 11:53:18 GMT

From section 3.6 in the Bluetooth Design Guidelines from Apple the upper limit for slave latency seems to be 4. With your connection parameter values you have given on this thread, I get slave latency limitation of 25 from the first rule in section 3.6 and slave latency limitation of 16 from the last rule. So from the rule "Slave Latency ≤ 4" is the limiting factor for slave latency so that you can increase the slave latency to 4, which means the peripheral is required to respond on every fifth connection event.

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Fri, 08 May 2015 11:17:53 GMT

Hi Stefan,

Thanks for the suggestion, what is the maximum slave latency i can increase for the existing connection interval which satisfies the iOS connection intervals.

Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Fri, 08 May 2015 10:30:35 GMT

I will let you know if we find out anything from Apple.

As a workaround, is it possible for you to increase the slave latency in order to save current while you are forced to stay in connection with the IOS device? Or otherwise to send connection parameter update request in order to increase the connection interval and thereby save current.

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Thu, 07 May 2015 14:06:48 GMT

We have to know the reason for this. For power saving this is important. The nRF will consume more power during this 10 second interval since it is connected state. Please let me know if you get reply any from Apple support group.

Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Thu, 07 May 2015 14:01:32 GMT

I see the 10 second interval with a sniffer, so I see directly the CONNECT_REQ and LL_TERMINATE_IND packets that are sent from IOS, so it is not an nRF51 issue.

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Thu, 07 May 2015 13:59:22 GMT

Ok, May be we can wait for reply from iOS developer. it is good that you can able to reproduce the issue what we are facing here :) . By the way which SDK we are using right now? . I am using SDK 6.1.0 . I hope it is not SDK issue. And how you are measuring the 10 second interval? Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Thu, 07 May 2015 13:51:41 GMT

This seems to be an IOS policy. This delay is not present on Android or with Master Control Panel (master emulator firmware). I have tried both with Iphone and Ipad and the delay is exactly 10 seconds from sending CONNECT_REQ to the peripheral until sending LL_TERMINATE_IND. I do not really understand the reason for the IOS to apply this delay. Asking around in the support group, nobody seems to have heard about any reason for it from apple either.

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Thu, 07 May 2015 13:24:56 GMT

Thanks Stefan, Please check and let me know. Are you also observing 10 second ? Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Thu, 07 May 2015 12:50:34 GMT

I can reproduce the problem now on ipad, and on iphone as well. I guess I was not disconnecting quickly enough after connecting. I will investigate what is going on and respond with any findings.

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Thu, 07 May 2015 12:23:06 GMT

Hi Stefan,

In the image, the five pulses are the LED blink on the nRF device. you can observe that the minimum connection establishment between the nRF and iOS device is 10 second.

Can you test once with iPAD device. We are not using iphone.

Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Thu, 07 May 2015 11:09:03 GMT

I tested this with ble_app_uart in SDK 8.0.0 together with IOS nRF_Toolbox_master UART version 1.8 and the nRF51 device disconnects right away. I see that because the advertising led starts to blink as soon as I press disconnect on the iphone. When the ble_app_uart application receives the "DISCONNECTED" callback, it will start advertising. So I am still not able to reproduce the problem.

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Thu, 07 May 2015 10:50:21 GMT

I added the image to the thread. In this image, are we looking at the current consumption of the nRF51 device? If so, are these 5 pulses BLE connection events, which then stop when you disconnect?

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Thu, 07 May 2015 10:40:43 GMT

The below is the new case registered URL

www.nordicsemi.com/.../21829

Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Thu, 07 May 2015 10:02:42 GMT

Hi Stefan, I have registered the new case and attached the snapshot .

The IOS version we are using is as follows. Ios 8.1.2 Device : Ipad3

The app we are using is the nRF_Toolbox_master UART which communicates with our nRF application which we developed.

You are right , I tested that also, i have checked the disconnet command coming from IOS and MCP device, both are same.(LL_TERMINATE_IND)

I saw the disconnection in the NRF side which is connected across the CRO.The IOS device device is sending the disonnection command in 3 second but the disonnection happens after 30 seconds only.

Note : If i send the disconnect command from the MCP to the nRf application, it disconnect soon.

Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Thu, 07 May 2015 09:32:44 GMT

I will also try to test with nRF_Toolbox_master UART app and try to reproduce the problem.

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Thu, 07 May 2015 09:31:53 GMT

Hi Anand

Can you please report what IOS version you have, what iphone version, and what app you are using?

Perhaps the best method is to use a BLE sniffer to identify the problem, i.e. to identify what is the difference between the disconnect from MCP and from IOS.

In my previous test with the IOS nRFToolbox HRM app and the ble_app_hrs example running on the nRF51 DK board, I see that the advertising led starts to blink immediately after I press disconnect on the IPhone (i.e. in the nRFToolbox HRM app). How do you see your disconnection? on the nRF51 device or on the iphone?

If you create a support case in the support portal, you can attach images, code and such. Go to www.nordicsemi.com an log in. Press "My page" and then "Register new case" in order to create a support case. Notify me here when you have created your case so I can notice your case and see your snapshot

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Wed, 06 May 2015 15:10:06 GMT

Hi Stefan,

I have tested the our nRF application with MCP. It connects and disconnects as soon as you send the connect/disconnect command from the MCP. Where as with iOS application it tooks 10 seconds to disconnect even though you send the disconnect command earlier than 10 seconds.

Regards, Anand Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Wed, 06 May 2015 14:27:32 GMT

I have posted the same question in IOS apple developer forum. No answer from them.

Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Wed, 06 May 2015 14:25:20 GMT

Hi Stefan, We have this issue from past 1 month, can you please let me know what could be the issue. Is it on iOS side or nRF side?

Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Wed, 06 May 2015 14:19:40 GMT

Hi Stefan,

Can you please send me the mail ID of yours , i will send you the snapshot.

Regards, Anand

RE: Connection interval issue between nRF51822 and iOS device

Anand Ramashetty — Wed, 06 May 2015 14:04:58 GMT

Hi Stefan,

We have developed our own iOS app to communicate with nRF. Anyway I have tested the nRF application with the IOS-nRF_Toolbox_master UART app, there also it is taking minimum 10 second to diconnect.

RE: Connection interval issue between nRF51822 and iOS device

Stefan Birnir Sverrisson — Wed, 06 May 2015 12:50:05 GMT

Hi Anand

What app are you using on the IOS that shows the 10 second connection? If you use IOS nRFToolbox HRM app together with the ble_app_hrs example on the peripheral you can see that the peripheral disconnects immediately and starts advertising.