Using the new Connection State module to decide role

[Chris]

I'm developing an application supporting concurrent central and peripheral connections and using the new Connection State module in SDK 10 to decide whether a BLE stack event should be handled by the central or peripheral event handler.

My ble_evt_dispatch() function is based closely on the Nordic ble_app_hrs_rscs_relay example, i.e.:

static void ble_evt_dispatch(ble_evt_t *p_ble_evt)
{
    uint16_t conn_handle;
    uint16_t role;

    ble_conn_state_on_ble_evt(p_ble_evt);   // Must be called before any event handler that uses conn state module

    // The connection handle should really be retrievable for any event type.
    conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
    role = ble_conn_state_role(conn_handle);

    if (role == BLE_GAP_ROLE_PERIPH)
    {   
        on_ble_peripheral_evt();
        ...
    }
    else if (role == BLE_GAP_ROLE_CENTRAL)
    {
        on_ble_central_evt();
        ...
    }
}

This worked fine until I had a scan timeout and discovered that the BLE_GAP_EVT_TIMEOUT handler in my on_ble_central_evt() was not getting called. On investigation I found that ble_conn_state_role() is returning BLE_GAP_ROLE_INVALID on a scan timeout because there is no connection so conn_handle is not set.

The ble_app_hrs_rscs_relay example has a BLE_GAP_EVT_TIMEOUT case in its on_ble_central_evt() function, but I wonder if this can ever get called. Shouldn't the ble_evt_dispatch() function include an explicit check for role == BLE_GAP_ROLE_INVALID in which it call functions to handle connectionless events such as BLE_GAP_EVT_TIMEOUT, or have I misunderstood how to use the ble_conn_state_role() function?

[run_ar]

So ble_gap_evt_timeout_t contains the src data fields(source). This will give you the GAP Timeout sources.

In the Relay example we handle
BLE_GAP_TIMEOUT_SRC_ADVERTISING in ble_advertising_on_ble_evt,
BLE_GAP_TIMEOUT_SRC_CONN are handled in on_ble_central_evt.
BLE_GAP_TIMEOUT_SRC_SCAN are not handled as there is no timeout configured in the example, so this would have to be stopped using sd_ble_gap_scan_stop.
BLE_GAP_TIMEOUT_SRC_SECURITY_REQUEST is not handled in the experimental release of the peer manager, but we have a task to add this to the "production" release.

If you want to handle BLE_GAP_TIMEOUT_SRC_SCAN I suggest you do this in on_ble_central_evt. Note that connecting and scanning is only used in the central role (or observer role for scanning), which is why this is handled as a central event. Check src like this:
if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_CONN)

[Chris]

Thanks. I assume it's because there is no connection so p_ble_evt->evt.gap_evt.conn_handle is set to BLE_CONN_HANDLE_INVALID