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HCI Connection Timeout too often.

Hello,

in my Scatternet, I often receive HCI Connection Timeouts. Depending on the settings this happens once or twice over half a day between 10 Nodes or it could happen multiple times. The Scatternet does not have circles but is built as a tree. The RSSI between nodes was not worse than -80. I do send some packets between devices from time to time.

Here's my Setup:

All Devices are connected to one, two or three other devices. Slave and Central at the same time:

  • 10 nRF51 Dongles with S130 v2.0.0-8 alpha
  • Connection interval 10ms
  • Supervision timeout: 6000 ms

Meanwhile, they scan with the following settings:

  • Scan Interval: 20ms
  • Scan Window: 4ms

And they advertise:

  • Advertising Interval 100 ms

I initialize the Softdevice with NRF_CLOCK_LF_XTAL_ACCURACY_500_PPM, which is the most forgiving value that I could possibly pick. I tried with other values but the connection seemed to be less stable.

Now here are my questions:

Is there anything I could be doing wrong in my program code? I do not block interrupts or anything so I would guess that there's nothing that I could be doing wrong which would cause HCI Connection Timeouts. Because I thought that Connections are fully handled by the SoftDevice.

With the given parameters I would not expect connection losses to happen this often. Can you confirm this with internal measurements that this is really to be expected?

Marius