nrf51822 starts advertising on disconnect. How to stop it??

RE: nrf51822 starts advertising on disconnect. How to stop it??

brianreinhold — Tue, 12 Jan 2021 10:04:29 GMT

Well, I set the type to BLE_GAP_ADV_TYPE_ADV_IND and it is scannable; the chip responds to a scan request. I don't recall what happens if I set the type to BLE_GAP_ADV_TYPE_ADV_SCAN_IND.

I see for SoftDevice s130 I have these:

#define BLE_GAP_ADV_TYPE_ADV_IND 0x00 /**< Connectable undirected. */
#define BLE_GAP_ADV_TYPE_ADV_DIRECT_IND 0x01 /**< Connectable directed. */
#define BLE_GAP_ADV_TYPE_ADV_SCAN_IND 0x02 /**< Scannable undirected. */
#define BLE_GAP_ADV_TYPE_ADV_NONCONN_IND 0x03 /**< Non connectable undirected. */

But there is no mention here that the 'SCAN" option is not connectable.

But in s140v6 I have these which is a little more extensive and clearer:

#define BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED                   0x01   /**< Connectable and scannable undirected
                                                                                        advertising events. */
#define BLE_GAP_ADV_TYPE_CONNECTABLE_NONSCANNABLE_DIRECTED_HIGH_DUTY_CYCLE  0x02   /**< Connectable non-scannable directed advertising
                                                                                        events. Advertising interval is less that 3.75 ms.
                                                                                        Use this type for fast reconnections.
                                                                                        @note Advertising data is not supported. */
#define BLE_GAP_ADV_TYPE_CONNECTABLE_NONSCANNABLE_DIRECTED                  0x03   /**< Connectable non-scannable directed advertising
                                                                                        events.
                                                                                        @note Advertising data is not supported. */
#define BLE_GAP_ADV_TYPE_NONCONNECTABLE_SCANNABLE_UNDIRECTED                0x04   /**< Non-connectable scannable undirected
                                                                                        advertising events. */
#define BLE_GAP_ADV_TYPE_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED             0x05   /**< Non-connectable non-scannable undirected
                                                                                        advertising events. */
#define BLE_GAP_ADV_TYPE_EXTENDED_CONNECTABLE_NONSCANNABLE_UNDIRECTED       0x06   /**< Connectable non-scannable undirected advertising
                                                                                        events using extended advertising PDUs. */
#define BLE_GAP_ADV_TYPE_EXTENDED_CONNECTABLE_NONSCANNABLE_DIRECTED         0x07   /**< Connectable non-scannable directed advertising
                                                                                        events using extended advertising PDUs. */
#define BLE_GAP_ADV_TYPE_EXTENDED_NONCONNECTABLE_SCANNABLE_UNDIRECTED       0x08   /**< Non-connectable scannable undirected advertising
                                                                                        events using extended advertising PDUs.
                                                                                        @note Only scan response data is supported. */
#define BLE_GAP_ADV_TYPE_EXTENDED_NONCONNECTABLE_SCANNABLE_DIRECTED         0x09   /**< Non-connectable scannable directed advertising
                                                                                        events using extended advertising PDUs.
                                                                                        @note Only scan response data is supported. */
#define BLE_GAP_ADV_TYPE_EXTENDED_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED    0x0A   /**< Non-connectable non-scannable undirected advertising
                                                                                        events using extended advertising PDUs. */
#define BLE_GAP_ADV_TYPE_EXTENDED_NONCONNECTABLE_NONSCANNABLE_DIRECTED      0x0B   /**< Non-connectable non-scannable directed advertising
                                                                                        events using extended advertising PDUs. */

RE: nrf51822 starts advertising on disconnect. How to stop it??

Einar Thorsrud — Tue, 12 Jan 2021 08:00:05 GMT

Hi,

[quote user="brianreinhold"]So I wasn't sure what BLE_GAP_ADV_TYPE_ADV_SCAN_IND did and how it differed from BLE_GAP_ADV_TYPE_ADV_IND.[/quote]

I see. It is unfortunately not clear from the API documentation. To be specific BLE_GAP_ADV_TYPE_ADV_SCAN_IND is scannable, undirected and non-connectable. BLE_GAP_ADV_TYPE_ADV_IND is non-scannable, undirected and connectable.

RE: nrf51822 starts advertising on disconnect. How to stop it??

brianreinhold — Mon, 11 Jan 2021 17:09:58 GMT

Yes, but it includes in that list of non-connectable modes BLE_GAP_ADV_TYPE_ADV_SCAN_IND which, as you describe it, is connectable as I understand it. So I have been using BLE_GAP_ADV_TYPE_ADV_IND instead which responds to scan requests as well. So I wasn't sure what BLE_GAP_ADV_TYPE_ADV_SCAN_IND did and how it differed from BLE_GAP_ADV_TYPE_ADV_IND.

RE: nrf51822 starts advertising on disconnect. How to stop it??

Einar Thorsrud — Mon, 11 Jan 2021 15:34:30 GMT

Hi,

[quote user=""]How can I shut this thing up?[/quote]

The SoftDevice itself will not start to advertise on it's own. Are you by any chance using the advertising module (ble_advertising.c/.h)? If so, it will start advertising after a BLE_GAP_EVT_DISCONNECTED event.

[quote user=""]

"An application can start an advertising procedure for broadcasting purposes while a connection is active. After a BLE_GAP_EVT_CONNECTED event is received, this function may therefore be called to start a broadcast advertising procedure. The advertising procedure cannot however be connectable (it must be of type BLE_GAP_ADV_TYPE_ADV_SCAN_IND or BLE_GAP_ADV_TYPE_ADV_NONCONN_IND)."

There you state that a scannable advertisement is not connectable. What do you mean by 'scannable'?

[/quote]

"Scannable" here means that the device is scannable, i.e. will listen for scan requests and reply with a scan response. I think you are reading the documentation wrong, though. The key here is that the S130 SoftDevice (unlike SoftDevices for the nRF52) only supports a single connection in the peripheral role. Therefor, the point here is that when there is an active connection, you can only advertise in non-connectable mode.