Problem of multi-link using the relay unit

RE: Problem of multi-link using the relay unit

FormerMember — Mon, 25 Apr 2016 13:28:17 GMT

Could you upload your code so that I can take a look at it and test it? If you don't want to upload it here, you can create a new support case from www.nordicsemi.com, link to this thread, upload the code, and direct the case to me.

RE: Problem of multi-link using the relay unit

KIYOMI — Mon, 25 Apr 2016 04:42:02 GMT

I'm sorry reply late. I have been tested using the "ble_app_hrs_rscs_relay example", but it does not go well. We have the following modifications for to fit into our system.

Add service
After connecting with the peripheral, to start the advertising of relays

We use SDK 9 and S130 v1.0.1. How should we analyze? Central can connect with a peripheral directly, but is it better to prohibit it?

RE: Problem of multi-link using the relay unit

FormerMember — Wed, 20 Apr 2016 08:53:12 GMT

It should not be any problem for the relay to be and master and a slave at the same time. Do you see the same problem if you test the ble_app_hrs_rscs_relay example in the SDK as well?

Which SDK and softdevice version do you use? SDK 11 and S130 v.2.0.0?

RE: Problem of multi-link using the relay unit

KIYOMI — Wed, 20 Apr 2016 08:40:07 GMT

Thanks for the quick answer. Unstable communication is not in either of the above conditions.After all has been disconnect, via a peripheral device again relay, it may not be able to connect to the central.

Here describes "unstable communication".

When there are two communication paths as described previously (see below);

Peripherals’ communication paths:

A peripheral can directly communicate with the central.
A peripheral can communicate with the central via a relay station.

Communication with path 1 is fine, but communication with path 2 has a problem. The peripheral can establish communication with a relay device, then it may or may not establish the communication with the central (unstable communication). We tested the environment only with path 2, then the communication was established fine. The question is if there is any known issue to have two types of paths we currently have?

RE: Problem of multi-link using the relay unit

FormerMember — Wed, 20 Apr 2016 06:11:54 GMT

What do you mean by unstable communication? When the relay device is connected to a peripheral, is the connection unstable? Or is it hard for the relay device to re-connect to the peripheral, because the central device is already connected to the peripheral?

RE: Problem of multi-link using the relay unit

KIYOMI — Wed, 20 Apr 2016 04:32:38 GMT

I'm sorry reply late. I'll explain in detail. Goal we want to achieve:

Establishment of communication between the central and peripherals The communication may or may not be established via a relay station.

As the specifications of the communication, we want to achieve 1 and 2 below.

Conditions:

Peripheral: Starts Advertising
Relay station: Scanning, then starts advertising after connected to a peripheral.
Central: Scanning (multiple connections)

Specifications of the communication:

Communication A peripheral sends data to the central, and then the central sends the data back to the peripheral.
Disconnection of the communication: After the peripheral receives the data from the central in 1. above, the peripheral verifies the received data, and when the data is correct, then it disconnects the communication.

Issue: When peripherals are placed in two cases of locations as described below, communications between peripherals and the central may become unstable.

Peripherals’ communication paths:

A peripheral can directly communicate with the central.
A peripheral can communicate with the central via a relay station.

Question: Is the issue solved, i.e., the communication becomes stable, if peripherals are placed in locations where they can only communicate with the central via a relay station (case 2. above).

RE: Problem of multi-link using the relay unit

FormerMember — Thu, 07 Apr 2016 12:14:44 GMT

Okay, I see. After both peripherals have disconnected from the relay device, can the central device see that the relay device is advertisting? When I test what you describe here, it works without any problems.

RE: Problem of multi-link using the relay unit

KIYOMI — Wed, 06 Apr 2016 08:18:22 GMT

Thanks for the quick answer. I am sorry that the description was not sufficient. My problem is not that the two peripherals can not connect. In the following 3rd step, Central can not respond to advertising from the relay. Central can respond the advertising from the peripheral. Do you know the reason why the Central can not respond?

1st step：first communication 　　　　peripheral -> relay -> central -> relay -> peripheral 2nd step:all disconnect 3rd step:second communication relay -> central : NG

RE: Problem of multi-link using the relay unit

FormerMember — Mon, 04 Apr 2016 11:32:36 GMT

ble_app_hrs_rscs_relay can connect to two peripherals without any problems. Remember that the advertising devices has to have the same device name, because ble_app_hrs_rscs_relay filters on device name: see on_ble_ev(..) --> case BLE_GAP_EVT_ADV_REPORT