Connections Clarification

[s. hoang]

New to BLE and nRF51822. I need some explanation and clarification of connections and connection intervals. Can I get a overview of how the nRF51822 or answer some questions?

Is it correct that using the sd_ble_gap_ppcp_get() is how to get the connection information and that the connection information is updated on BLE_GAP_EVT_CONNECTED AND BLE_GAP_EVT_CONN_PARAM_UPDATE events?

BLE_GAP_EVT_CONN_PARAM_UPDATE implies the master has complete control of the connection interval. Are the MIN/MAX connection intervals sent by the peripheral during advertising "suggested" limits?

If the master does control the connection parameters, is this something done automatically at this link layer or does the master's application have control?

What happens when the connection interval is exceeded? Is there an error or just a GAP disconnect event? i.e. How do I tell what caused disconnect event?

If I have a peripheral that will only have new data to send every ten seconds, will the link layer maintain the connection even though ten seconds exceeds the absolute connection interval of 4.0 seconds?

Finally, a example of what I am seeing on a board that has a external 32khz issue. If the external 32khz clock wasn't functioning properly. What would happen?
Would the connection initially be made but the the supervision timeout would hit and cause a disconnect?
Could data still be sent successfully before that supervision timeout?

[Ole Morten]

I'd suggest you take a look at this for an explanation of connection parameters and how that works.

If your low frequency crystal isn't running correctly, you'll normally see a hang when enabling the softdevice. If the precision you give when initializing the softdevice is not correct, you may see link losses due to the timing going bad at some random later time. You can check the reason for a disconnect by looking at the reason field of the ble_evt_gap_disconnected_t struct. If you suspect this, I'd recommend trying different values, and possibly move to the RC oscillator to see if that helps. Take a look at this for the different low-frequency clock source options.