Hi Jacob,
On Thu, Apr 20, 2017 at 02:21:01PM -0700, Jacob Rosenthal wrote:
> I think the default intervals are here, which should be sufficiently over
> 20ms
> /** 30 ms. */
> #define BLE_GAP_ADV_FAST_INTERVAL1_MIN (30 * 1000 / BLE_HCI_ADV_ITVL)
> //48
>
> /** 60 ms. */
> #define BLE_GAP_ADV_FAST_INTERVAL1_MAX (60 * 1000 / BLE_HCI_ADV_ITVL).
> //96
>
> /** 100 ms. */
> #define BLE_GAP_ADV_FAST_INTERVAL2_MIN (100 * 1000 / BLE_HCI_ADV_ITVL)
> //160
>
> /** 150 ms. */
> #define BLE_GAP_ADV_FAST_INTERVAL2_MAX (150 * 1000 / BLE_HCI_ADV_ITVL)
> //240
>
> or I can even force to the higher ones in bleprph:
>
> adv_params.itvl_min = BLE_GAP_ADV_FAST_INTERVAL2_MIN;
> adv_params.itvl_max = BLE_GAP_ADV_FAST_INTERVAL2_MAX;
[...]
> > <https://devzone.nordicsemi.com/users/580/olha/>
> > In logs, interval advertises as adv_itvl_min=0 adv_itvl_max=0, on
> > connection logs ive seen both itvl=9 and itvl=12, not sure what that maps
> > to yet though..
These are advertising intervals, i.e., how frequently the device sends
out an advertisement, and not relevant here. BLE has a lot of
"intervals," so I don't fault you for getting confused!
The interval of importance here is the connection interval, i.e., how
frequently the two connected peers attempt communication.
I think adjusting the connection interval is not the best solution for
the supervision timeout problem. If you increase the interval, this
might help maintain the connection, but it will also impair response
time between the two devices. The correct setting to increase, in my
opinion, is the supervision timeout. By increasing this, you allow the
peripheral device to stay quiet for a longer period of time without the
connection getting dropped.
Regardless of which parameter you change, there are two ways to do it:
1. Configure the central device such that it initiates connections
with the preferred settings (this is what Vipul suggested in his
newtmgr diff).
2. Have the peripheral device request a connection parameter update
after the connection is established. With NimBLE, you would use
the ble_gap_update_params() function for this
(https://mynewt.apache.org/latest/network/ble/ble_hs/ble_gap/functions/ble_gap_update_params/).
Option 1 is the reliable way to do this. With option 2, the central may
choose to disregard your requested parameters, so you're really at the
central's mercy.
Chris
