ble_advdata_encode returns SVC Handler Missing

Question

I have a project that generally operates as a typical peripheral, but occassionally sends advertising packets of type BLE_GAP_ADV_TYPE_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED. In the process of broadcasting these non-connectable packets, I have to call ble_advdata_encode. Usually this is not a problem, but sometimes it returns error 0x01 (SVC Handler Missing). When I look at documentation of ble_advdata_encode, it says it should return either NRF_SUCCESS, NRF_ERROR_INVALID_PARAM, or NRF_ERROR_DATA_SIZE. I'm also not picking up on any pattern that this behavior follows. Can anyone enlighten me as to what might cause ble_advdata_encode to return error 0x01 (SVC Handler Missing)? 
 SDK: 15.0.0_a53641a 
 Soft Device: 6.0.0 
 IDE: Keil uVision5

Tanner · Accepted Answer

The root of the problem was in our function for broadcasting arbitrary advertising packets. It turns out that the length value in the advertising data structure in the global ble_gap_adv_data_t structure is updated with every packet to the length of that packet. If a longer packet is broadcast following a shorter packet, an error is returned. The solution was simply to update the length value for every broadcast packet. Here is what we're currently using to broadcast arbitrary advertising packets: 
 static ble_gap_adv_data_t m_bcast_data =	//structure that contains a pointer to encoded advertising data and the length of that data
{
	.adv_data =
	{
 .p_data = m_enc_bcast_data,
 .len = BLE_GAP_ADV_SET_DATA_SIZE_MAX
	}
};	

/**@brief Function for broadcasting advertising packets.
 *
 * @details Provide a pointer to the packet data, provide the length of the data
 * Function returns true when packet is sent successfully, false if tranmission fails.
 *
 * */
bool broadcast_packet( uint8_t* data, uint8_t length )
{
	bool success = true;
	ble_advdata_t adv_data;
	ble_gap_adv_params_t adv_params;
	ble_advdata_manuf_data_t mfg_data;

	//clear data structures
	memset( &adv_data, 0, sizeof(adv_data) );
	memset( &adv_params, 0, sizeof(adv_params) );
	memset( &mfg_data, 0, sizeof(mfg_data) );
	
	//global m_bcast_data.adv_data.len needs to be reset between packets
	//when a packet is sent, len is updated to the packet length (truncating any trailing zeros in the packet)
	//if a longer packet is sent after a shorter packet without updating len, ble_adv_data_enc will return 0x0C -- invalid data size
	//apparently, len is updated AFTER the size check in ble_adv_data_enc -->> manuf_specific_data_enc
	m_bcast_data.adv_data.len = BLE_GAP_ADV_SET_DATA_SIZE_MAX;	
	
	//check packet length, truncate if too long
	if( length > BROADCAST_LENGTH_MAX )
 length = BROADCAST_LENGTH_MAX;

	//configure custom data
	mfg_data.company_identifier = BROADCAST_COMPANY_ID;
	mfg_data.data.p_data = data;
	mfg_data.data.size = length;

	//point advertising data structure to custom data
	adv_data.p_manuf_specific_data = &mfg_data;

	//encode advertising data in m_bcast_data structure
	if( ble_advdata_encode( &adv_data, m_bcast_data.adv_data.p_data, &m_bcast_data.adv_data.len ) != NRF_SUCCESS )
 return !success;

	//set advertising parameters
	adv_params.primary_phy = BLE_GAP_PHY_1MBPS; 
	adv_params.duration = 12; //Duration, in 10ms units
	adv_params.properties.type = BLE_GAP_ADV_TYPE_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED;	//Broadcast packets are non-connectable, non-scannable, and undirected
	adv_params.interval = 0x30; //Interval, in 625us units

	//stop any advertisement activity
	sd_ble_gap_adv_stop( m_adv_handle );

	//configure the packet with specified parameters
	if( sd_ble_gap_adv_set_configure(&m_adv_handle, &m_bcast_data, &adv_params) != NRF_SUCCESS )
 return !success;

	//start broadcast
	if( sd_ble_gap_adv_start( m_adv_handle, APP_BLE_CONN_CFG_TAG ) != NRF_SUCCESS )
 return !success;

	return success;
}

/* We need to return to connectable advertising once the broadcast packet terminates
 Add this to ble_evt_handler:
 
 case BLE_GAP_EVT_ADV_SET_TERMINATED:
 if( m_conn_handle == BLE_CONN_HANDLE_INVALID )
 {
 advertising_init();
 advertising_start();
 }
 break; */

ble_advdata_encode returns SVC Handler Missing

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