Disconnection evet error 0x3E when extra services is added

[User1321]

Hi Nordic, 

I had an initial project with a multilink central connecting to several peripherals through a NUS service, the system is working OK but then I added another connection to a peripheraö (smartwatch) having the Heart Rate service.

After that is done, I get issues in the initial connection to the NUS peripherals (the smartwatch is NOT advertising): if I start the central and 2 NUS-peripherals are simultaneously advertising, the central will connect OK to on of them and to the second one, it will have connection and reconnections indicating an 0x3E error. If I turn on the NUS peripheral one by one, the connection to each of them is OK in all cases.

If i remove the part of the code where the hrs is initialized, both connections occur properly without the previously described issue.

The timeout is 5s, it was working properly without adding the hrs in the services_init(). Any idea how can I fix this issue?

The central and NUS peripherals are nordic devices with the nRF52840 using the sdk_15.3 and s140.

 Thanks :)

[Kenneth]

Hi,

When establishing a connection this will have highest priority:
https://infocenter.nordicsemi.com/topic/sds_s132/SDS/s1xx/multilink_scheduling/priorities_and_events_intro.html

It may not be a good idea for a central role to initiate connection to two peripheral devices at the same time due to this, instead add a short delay (e.g. a few seconds and/or until connection parameters or encryption is finished for the first link) before you establish your second link.

Best regards,
Kenneth

[User1321]

how can this delay be added? with the SLAVE_LATENCY?

But is it not strange that this error is happening when the other two services are initialized?

[Kenneth]

I assume that your current implementation start scanning again on the connection event, I suggest to instead start an app_timer with a 2-3 second timeout before you start scanning again. 

User1321 said:

But is it not strange that this error is happening when the other two services are initialized?

Not really, but if you want to dig deeper into exact cause here you would need to provide two nRF sniffer logs for each link.

Best regards,
Kenneth