what happen when there are more than 8 devices and more than one hosts?

[huxinyao]

my project requires a simultaneously data-collection from 13 IMUs sensors which we built with NRF51822 + BNO055 (IMU)

we used the Gazelle mode, I understand each host can connect up to 8 devices. 

Let's say we set the Pipeline ID of the devices as Pipe0, Pipe1......Pipe7, ....Pipe8.... until there is Pipe12. (13 devices)

And there are two Host, Host 1 and Host 2, both connected to PC via USB serial port

Is it possible that we can get all the data from the 13 pipeline? 

Or, can we make sure that the Pipe0, pipe1......pipe7 keep communicateing with Host1. And pipe8, pipe9.... Pipe 12 keep communicate with Host2?

What should we do if we want to build such network?

 

[ovrebekk]

Hi

What kind of data rate and packet interval do you expect from each of the 13 sensors? 

Using two receivers is one way to achieve more than 8 devices, just make sure to use a different channel map in the two hosts so you don't get RF interference between them. 

It is also possible to have one Gazell host receive data from more than 8 devices, but this is a bit more tricky from an implementation point of view. 

The best way to do it if you want to minimize packet collisions between the different devices is to have the devices using two separate groups of channels.

For this to work the timeslot period of the devices should be twice that of the timeslot period in the host, and you have to assign channels to the device groups and host like this:

Device group 1 can use channels A, C and E
Device group 2 can use channels B, D and F
The host must use all channels, A, B, C, D, E and F

With this kind of setup you will avoid interference between the two device groups, and because the devices use double the timeslot period they should be able to synchronize to the host even if they use fewer channels. 

You can use more or less than 3 channels on the devices if you want, just make sure that the host uses twice as many channels, and configure the channels in a similar pattern as my example above. 

Then you can have one group of devices using device group 1 and pipes 0-7, and a second group of devices using device group 2 and pipes 0-7, for a total of 16 supported devices. 

Best regards
Torbjørn