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S120 throughput

Hi to all!

I have few questions about throughput when using s120:

  1. What is the max number of packets that could be send/received in one connection interval when using S120? (s120 specification, chapter 13 says 1tx/1rx, Hung Bui in post says 2tx/1rx, other definitions i didn't find...)
  2. A bit more tricky... In my project, my device connects up to 5 devices, some of them are smart devices. Now I'm wondering what is the best way of setting up connection interval?

Considering that smart devices have different limitations e.g. if I set min connection interval to 20 ms and max to 50ms then some of "smart" devices will set connection interval to 37.5ms. There is no problem until some other device can't communicate at such interval (Is this possible?). Who or what gurantee to me that devices will have a common factor? If not probably there will occure some collisions and connections could get dropped if supervision timeout is not realy long long.

If i refer to equation in s120 specs, chapter 11.4 where is written that connection interval should be >= "Number of devices" * Teeo + scanWindow + Tscan_reserved... During testing with 20ms connection interval some of devices get disconnected. Increasing it up to 50ms helps and connections get stable, but now is throughput 400KBps (1 packet per interval * 20 * 1/0.05) and it's to low... Is there something i can do (maybe more sophisticated way to set connection intervals) or this is the max what can i reach with s120?

Thank you!

BR Matej

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  • Hi Hung Bui!

    1. Thank you for explanation about number of packets on connection interval...
    2. I would like to know details about setting those paramaters - that i can achive max throughput. I have 5 devices connected and i want to have max throughput for each device e.g. if i have connected just one device, then i assume that i can use min possible connection interval 7.5ms and min scan window 2.5ms... after that i would like connect to second device -> so i need to increase/update existing connection intervals, after that i'am able to create new connection. According to connection interval changes also scanning interval should be changed...
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  • Hi Hung Bui!

    1. Thank you for explanation about number of packets on connection interval...
    2. I would like to know details about setting those paramaters - that i can achive max throughput. I have 5 devices connected and i want to have max throughput for each device e.g. if i have connected just one device, then i assume that i can use min possible connection interval 7.5ms and min scan window 2.5ms... after that i would like connect to second device -> so i need to increase/update existing connection intervals, after that i'am able to create new connection. According to connection interval changes also scanning interval should be changed...
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