BLE_GAP_EVT_CONNECTED event is not triggered

[Rekha]

Hi all,

I have checked in Nordic Devzone for this query but no luck in finding solution for my query.

I am using nrf52832 and configured as central and peripheral.

my device will scan and store peer address in flash and then connect to stored address later.

when i connect to peer address using sd_ble_gap_connect it returns NRF_SUUCESS but BLE_GAP_EVT_CONNECTED  is not triggered.

this issue occurs only for some peripherals and some peripheral i can able to connect and it triggers event as well.

tested with one of the example code: when i try to connect  peripheral  device programmed with ble_app_uart code this issue occurs where  BLE_GAP_EVT_CONNECTED  is not triggered.

but the same peripheral connects successfully through my Android phone.

i am unable understand what is the issue.

Please guide...

Thanks

Rekha

[Einar Thorsrud]

Hi,

You should always get either BLE_GAP_EVT_CONNECTED or BLE_GAP_EVT_TIMEOUT unless you cancel the connection by a call to sd_ble_gap_connect_cancel(), as you can see from this MSC. Can you share your code so that we can check to see if there is any possibility of you canceling the connection or missing an event?

[Rekha]

Hi i changed scan parameter timeout = 0x01 instead of 0. now i am getting ble gap event timeout error in BLE_GAP_EVT_TIMEOUT event.

How to solve

Thanks

[Einar Thorsrud]

Hi,

You cannot do this in a loop. You have to wait for a BLE_GAP_EVT_CONNECTED or BLE_GAP_EVT_TIMEOUT event before you can call sd_ble_gap_connect() for the second time.

[Rekha]

Hi 

That is where the risk is - if i set timeout device is not getting connected within that short span. hence i disabled timeout. suppose peripheral device is not in the vicinity, even then my device will still wait for the connection therefore i am unable to connect to next devices.

How much time does a central requires to connect peripheral?

Thanks

[Einar Thorsrud]

Rekha said:

That is where the risk is - if i set timeout device is not getting connected within that short span. hence i disabled timeout. suppose peripheral device is not in the vicinity, even then my device will still wait for the connection therefore i am unable to connect to next devices.

 Yes. That is why a timeout is usually sensible.

Rekha said:

How much time does a central requires to connect peripheral?

The time depends on the advertising interval of the peripheral, and the RF environment (noise/interference), which can lead to packet loss. This is because you have to receive an advertising packed in order to connect, and then send a successful connection request. If the time between advertisement packets (advertising interval) is long, or packets are lost, it will take longer time to connect. This are all inherent properties of BLE, and not directly related to the nRF devices.

[Rekha]

So the best way is to set time out to 0x20 and loop sd_ble_gap_connect().

after one successful connection with peripheral , when central tries to connect to next peripheral will i get successful connection?

can two peripheral devices connects to the same central in this way?

Thanks

[Einar Thorsrud]

Yes. The SoftDevice support up to 20 concurrent connections, and it does not matter if it is in central or peripheral role. You have to configure it to support this many connections, though. You should set NRF_SDH_BLE_TOTAL_LINK_COUNT and NRF_SDH_BLE_CENTRAL_LINK_COUNT to whatever number you need in your projects sdk_config.h. You also need to adapt your application to actually keep track of the connections.

[Rekha]

Hi Thanks for the information.

I have already set NRF_SDH_BLE_TOTAL_LINK_COUNT = 8 and NRF_SDH_BLE_CENTRAL_LINK_COUNT = 7 and NRF_SDH_BLE_PERIPHERAL_LINK_COUNT  = 1

and 

Einar Thorsrud said:

You also need to adapt your application to actually keep track of the connections.

how do i do this?

can you please  explain it in detail?

thanks

[Einar Thorsrud]

Rekha said:

how do i do this?

can you please  explain it in detail?

Please refer to the BLE Multi-link Example which demonstrates this.

[Rekha]

Thank you so much for your constant support.

i will look into the example.