About the muti connection of NRF51

RE: About the muti connection of NRF51

ketil — Fri, 23 Mar 2018 11:29:55 GMT

Hi,

I talked to our SDK team and they had the following to say about your case:

In principal, what he is trying to do is possible. The main issue is that he needs to adjust the db_discovery module, and each time there is a SoftDevice call, if it returns busy, he needs to have some kind of retry mechanism.

We are planning to include a new module inside db_discovery module for handling this but that is going to be included in a future version of the SDK.

A possible ‘simple’ work around, is to wait for the end of the discovery before doing a security procedure on another link or even before scanning again.

Ketil

RE: About the muti connection of NRF51

sq — Mon, 19 Mar 2018 07:15:50 GMT

>>2. call API "sd_ble_gattc_primary_services_discover"to start to discover,
>>then call API "sd_ble_gap_scan_start()"before discover complete event is coming.>This should work.

I don't think so. my nrf51 run ble_central_and_peripheral example.

I called call API "sd_ble_gattc_primary_services_discover"to start to discover, in HOST MCU side.
then call API "sd_ble_gap_scan_start()"before discover complete event is coming.
Sometimes the service discover is wrong, discover command seems be discard by NRF51 chip.(about 1/10).So I think these two APIs may be conflict with each other.

RE: About the muti connection of NRF51

ketil — Fri, 09 Mar 2018 11:50:16 GMT

Hi,

This will not work. You are not able to perform scanning whilst connecting. You will need to wait till the connection is completed.
This should work.
This should work. Be careful to pass the correct conn_handle to sd_ble_gattc_primary_services_discover og sd_ble_gap_authenticate.

Ketil

RE: About the muti connection of NRF51

sq — Fri, 09 Mar 2018 02:15:31 GMT

Maybe my question is not good enough, whether it is a problem if I do like below.
1. call API "sd_ble_gap_connect()" to connect, then call API "sd_ble_gap_scan_start()" to scan
before connection success.
2. call API "sd_ble_gattc_primary_services_discover"to start to discover,
then call API "sd_ble_gap_scan_start()"before discover complete event is coming.
3.call API "sd_ble_gap_authenticate()" to pair with peripheral1, then call API "sd_ble_gap_connect()"" to peripheral2
before pair successfully with peripheral1.

I build one task central1, another task for central2. so the situation above may occur.
they sometimes cause problem according to my test.

For some APIs, before their corresponding event coming. another API shouldn't be called.
Is it right?

RE: About the muti connection of NRF51

ketil — Thu, 08 Mar 2018 12:58:52 GMT

Hi,

Are you using the provided example in SDK 9.0 or have you written your own code?

Anyways, I highly recommend that you change to SDK 11.0 and S130 V2.0.x. According to the SDK 11.0 release notes there were significant improvements made to the multilink functionality:

** BLE **
- Multi-instance handling of Service client modules has been greatly 
  improved. The client examples now handle service discovery in the main
  application context. The main application context must manage which 
  client instance belongs to which connection link.
- The Multi-link Example has been modified to demonstrate multiple 
  client instances in a better way.

Please try to compile and test the SDK 11.0 BLE Multi-link Example.

Ketil

RE: About the muti connection of NRF51

sq — Thu, 08 Mar 2018 11:09:49 GMT

I have test with sdk9.0 like this,

1. Use nrf51 as central device, scan and connect with device1.
2. After connected successfully, start to scan again, then start to discover service.
3. I found the return value of discovering service is success, but sometimes the discover event is not coming.
4. If the discover event is success, pairing with device1, sometimes the paring event is not coming.
5. So If nrf51 scanning and discovering(or pairing) at the same time, some event will be abnormal discard.

So If nrf51 is discovering the service with device1, it can't scan at the same time.
if nrf51 is pairing with device1, it can't connect with device2 at the same time.
Is it true?

if I update the sdk from 9 to 11, is it same?

Thanks

RE: About the muti connection of NRF51

ketil — Thu, 08 Mar 2018 07:54:32 GMT

Hi,

Yes, the nRF51822 can connect to multiple peripherals (up to eight) when running as a central in SDK 11.0 and S130. S132 is only for nRF52 devices. We have an example demonstrating your exact questions.

Ketil