I am developing firmware for my Peripheral Device (nRF52840) using S140 (v7) and SDK 15.3. In my application, I will advertise (with advert payload changes) and support Smartphone app connect/disconnect to read and write custom characteristic values. Changing the payload was a challenge, but has been resolved using forum posts on this subject. I have created advertising_config(bool firstCall) to set up (firstCall=true) or update (firstCall=false) advertising. It is not updating with meaningful data yet, but it shows that (conceptually), updates work (toggles data between "SomeData!" and "TomeData!" every 10 sec).
// Config advertising.
static void advertising_config(bool firstCall)
{
ret_code_t err_code;
// Setup var to hold ble_advdata_t advert data.
ble_advdata_t advdata;
memset(&advdata, 0, sizeof(advdata));
// Setup var to hold ble_advdata_t scan resp data.
ble_advdata_t srdata;
memset(&srdata, 0, sizeof(srdata));
// Just use srdata to indicate that we want to expose the name provided in gap_params_init().
srdata.name_type = BLE_ADVDATA_FULL_NAME;
// Setup variable to hold manufacturer specific advert data
ble_advdata_manuf_data_t mfr_advdata;
memset(&mfr_advdata, 0, sizeof(mfr_advdata));
// Update mfr_data and add to advdata.
uint8_t data[10];
if(m_bufIdx == 0) { strcpy(data, "SomeData!"); }
else { strcpy(data, "TomeData!"); } //Our data to advertise
mfr_advdata.company_identifier = 0x0059; //Nordics company ID
mfr_advdata.data.p_data = data;
mfr_advdata.data.size = sizeof(data);
advdata.name_type = BLE_ADVDATA_NO_NAME;
advdata.p_manuf_specific_data = &mfr_advdata;
advdata.include_appearance = true;
advdata.flags = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
advdata.uuids_complete.p_uuids = m_adv_uuids;
// Initialize advertising parameters (used when starting advertising).
memset(&m_adv_params, 0, sizeof(m_adv_params));
m_adv_params.properties.type = BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED;
m_adv_params.p_peer_addr = NULL; // Undirected advertisement.
m_adv_params.filter_policy = BLE_GAP_ADV_FP_ANY;
m_adv_params.interval = APP_ADV_INTERVAL;
m_adv_params.duration = 0; // Never time out.
// Encode advdata to m_gapData[m_bufIdx]
err_code = ble_advdata_encode(&advdata, m_gapData[m_bufIdx].adv_data.p_data, (uint16_t *) &m_gapData[m_bufIdx].adv_data.len);
APP_ERROR_CHECK(err_code);
// Encode srdata to m_gapData[m_bufIdx]
err_code = ble_advdata_encode(&srdata, m_gapData[m_bufIdx].scan_rsp_data.p_data, (uint16_t *) &m_gapData[m_bufIdx].scan_rsp_data.len);
APP_ERROR_CHECK(err_code);
// Setup adverts. On first call, also set advert params.
if(firstCall)
{
err_code = sd_ble_gap_adv_set_configure(&m_adv_handle, &m_gapData[m_bufIdx], &m_adv_params);
APP_ERROR_CHECK(err_code);
}
else // Susequent calls - update payloady only.
{
err_code = sd_ble_gap_adv_set_configure(&m_adv_handle, &m_gapData[m_bufIdx], NULL);
APP_ERROR_CHECK(err_code);
}
// Toggle buffer index to toggle buffer used.
if(m_bufIdx == 0) {m_bufIdx ++;}
else {m_bufIdx = 0;}
}
My remaining challenge is getting advertising to restart after a Smartphone app disconnects. I have been using the Android nRF Connect app for testing.
I have tried using the hrs example app (\nRF5_SDK_15.3.0_59ac345\examples\ble_peripheral\ble_app_hrs) as a reference, but it does not work. Whenever I connect to it, read a characteristic value and then disconnect, its advertising does not restart after disconnect (stops when I connect to my dev kit using nRF Connect).
What works (not a feasible solution in the real world due to delay discussed following) is restarting advertising (sd_ble_gap_adv_start(m_adv_handle, APP_BLE_CONN_CFG_TAG);) when BLE_GAP_EVT_DISCONNECTED is passed to my ble_evt_handler() as shown below.
// Handle BLE events.
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
ret_code_t err_code = NRF_SUCCESS;
switch (p_ble_evt->header.evt_id)
{
case BLE_GAP_EVT_DISCONNECTED:
NRF_LOG_INFO("Disconnected.");
SEGGER_RTT_printf(0, "Disconnect Evt.\n");
sd_ble_gap_adv_start(m_adv_handle, APP_BLE_CONN_CFG_TAG);
m_conn_handle = BLE_CONN_HANDLE_INVALID;
break;
case BLE_GAP_EVT_CONNECTED:
NRF_LOG_INFO("Connected.");
SEGGER_RTT_printf(0, "Connect Evt.\n");
err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
APP_ERROR_CHECK(err_code);
m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
APP_ERROR_CHECK(err_code);
break;
The problem with this approach is that BLE_GAP_EVT_DISCONNECTED can come into ble_evt_handler() 3 - 12 minutes after nRF Connect disconnects from the peripheral.
If I can get a faster indication of disconnection, I can stick with the approach that I have now (just call sd_ble_gap_adv_start() after getting an indication of disconnection). Please advise how to change BLE GAP config to support this.
Optionally - if there is a way to setup auto-restart upon disconnection, that approach would be even better.
Maybe also worth consideration .... when I select Disconnect within the nRF Connect app, is it actually disconnecting or am I just seeing a timeout 3-12 min later (i.e. nRF Connect bug)?
Looking forward to a reply and all help and input is appreciated.
Mark J
