BLE Adv Interval

[mich_x]

I am working on S140 on nRF25840. I am using the ble_app_beacon sample. I want to set the advertising interval smaller than 100ms while using non-connectable mode. But the BLE_GAP_ADV_NONCON_INTERVAL_MIN stops me. I wonder if there is any reason to set the minimum to 100ms, can I change it to smaller?

My second question is what is mode BLE_GAP_ADV_TYPE_ADV_SCAN_IND. It says Scannable undirected. Does it mean mode BLE_GAP_ADV_TYPE_ADV_NONCONN_IND cannot be scanned?

[RK]

The reason is the BLE spec says that non-connectable advertising shall not have an advertising interval less than 100ms and the softdevice is certified to follow the spec.

Correct, ADV_NONCONN_IND cannot be scanned. Again those terms are buried in the incredibly long BLE spec.

ADV_DIRECT_IND    - connectable, not scannable, directed
ADV_IND           - connectable, scannable, undirected
ADV_NONCONN_IND   - not connectable, not scannable, undirected
ADV_SCAN_IND      - not connectable, scannable, undirected

[endnode]

Btw. BT 5.0 lifted this limitation for non-connectable adv. interval and Nordic team plans to update S140/132 stacks in the future...

[RK]

I didn't know that - I guess I have to read the whole bloody spec again.

[mich_x]

What if I use connectable mode, while the scan machine does not try to connect. Does it make the communication somehow wrong? Can I set the adv interval smaller than 100ms.

BTW, the spec is long. My deadline doesn't allow me to read them through. :(

[Petter Myhre]

The 100 ms limitation is only for non-connectable advertising. You can use connectable advertising with less than 100 ms. Doesn't make your communication "wrong".