BLE Master-Slave mode can avoid colision?

[zhangkui]

            We have 3 nRF52840 to establish a net. one for master device, One for Master device, One for HUB(Msater-Slave) device, and One for Slave device. The data flow is Slave device--> HUB(Master-Slave) device -->Master device.

             So there is two BLE link: one for the master device and the HUB device. One for the HUB device and the Slave device. For the HUB device , The most important design is to avoid the link colision. I think if the HUB connect the master first,  then connect slave, nRF52840 can arrange the anchor proper to avoid link colision. because if HUB connect the Master device, The master deivce deside the anchor point and notify the HUB the anchor point by connect req PDU. when the HUB decide the anchor pointer for slave connection, It can arrange it proper to avoid colision.

              So when the HUB connect the master device, It will disconnect the Slave device and rescan for the slave device for connect.

              But it fullfilled in the nRF52840 SDK, It just a guess, I can't confirm it. 

              Can Noridc engeneer confirm it, Or tell me the how the WInoff and winsize are caculated in the SDK?

              

             

[Karl Ylvisaker]

Hello,

Yes, the SoftDevice will handle this for you as detailed in the SoftDevice scheduling documentation.
When the SoftDevice is working in the multirole configuration (both central and peripheral role) it will use the Timeslot API to makes sure that there are no collision between the radio usage of each role.

Best regards,
Karl

[zhangkui]

So I want to confirm if the multirole device connect the slave device first , Can Nordic avoid the colision. We have test that it can't. But I think if the multirole device connect the master device first , It will be different.

Can you help confirm it?

[zhangkui]

you think nordic can avoid colision in both cases(multifold connect master device first  or  connect slave device first)?  We only set proper event length and connect interval. SDK can avoid collision.-------connect sequence have no effect.

Or  connect  sequined is very important.

[Karl Ylvisaker]

I can confirm that there will not be collisions between the radio usage of the different roles when the timeslot API is used to separate the two. The timeslot API is made for this specific reason, so that you can be certain that the radio is available to the specific role/function at a specific time. The connection sequence will not matter as long as both roles are provided an appropriate timeslot.

Best regards,
Karl

[zhangkui]

Ok, We have tested that the data throughput of multifold is less than one master connect two slaves. Maybe the reason is we set both connect interval and event length 7.5ms.  Can you give us some suggestion about setting for multitoles