Advertise on one channel at a time - app_timer problem

[Mathias Vandel]

Hi DevZone

I want to make a little beacon app, that advertises on channel 37 then waits 700 ms, advertises on channel 38, waits 700 and advertises on channel 39. The below is what i have implemented, yet it doesn't work. It seems like the timeout handler is never called and therefor it is never starting advertising.

static void timers_init(void)
{
	uint32_t err_code;
	APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false);
	
	err_code = app_timer_create(&channel_timer_id, APP_TIMER_MODE_REPEATED, channel_timeout_handler);
	APP_ERROR_CHECK(err_code);	
}

My timeout handler which switches the channel_mode

static void channel_timeout_handler(void *p_context)
{
	SEGGER_RTT_printf(0, "Channel timeout handler %d\n, channel_mode");
	
	if(m_channel_mode == 37)
	{
		m_channel_mode = 38;
	}
	else if(m_channel_mode == 38)
	{
		m_channel_mode = 39;
	}
	else if(m_channel_mode == 39)
	{
		m_channel_mode = 37;
	}
	
	advertising_stop();
	advertising_init(m_channel_mode);
	advertising_start();
}

And here is my advertising_init where i set what channel it advertises on

static void advertising_init(uint8_t channel_mode)
{
	
		SEGGER_RTT_printf(0, "Advertising init\n");
    uint32_t      err_code;
    ble_advdata_t advdata;		
		ble_gap_adv_ch_mask_t ch_mask; // channel mask
		
	
	  uint8_t flags = BLE_GAP_ADV_FLAG_BR_EDR_NOT_SUPPORTED;
	
		ble_uuid_t adv_uuids[] = 	
		{
				{BLE_CUSTOM_16UUID, 		BLE_UUID_TYPE_BLE}
		};

    // Build and set advertising data.
    memset(&advdata, 0, sizeof(advdata));
    advdata.name_type             = BLE_ADVDATA_NO_NAME;
		advdata.include_appearance		= false;
		advdata.flags 								= flags;
		
    err_code = ble_advdata_set(&advdata, NULL);
    APP_ERROR_CHECK(err_code);
		

		// Prepare the Manufacturer specific data packet
		ble_gap_addr_t gap_addr;
		sd_ble_gap_address_get(&gap_addr);
		ble_advdata_manuf_data_t manuf_data;
		
		manuf_data.company_identifier           = 0x028C; // 0x028C; // NanoLink Aps company ID
		//www.bluetooth.org/.../company-identifiers
		
		manuf_data.data.p_data									= gap_addr.addr;
		manuf_data.data.size                    = sizeof(gap_addr.addr);
		
    advdata.uuids_complete.uuid_cnt = sizeof(adv_uuids) / sizeof(adv_uuids[0]);
    advdata.uuids_complete.p_uuids  = adv_uuids;
		
		advdata.p_manuf_specific_data   = &manuf_data;

    err_code = ble_advdata_set(&advdata, NULL);
    APP_ERROR_CHECK(err_code);
	
    // Initialize advertising parameters (used when starting advertising).
    memset(&m_adv_params, 0, sizeof(m_adv_params));	
		
		m_adv_params.type					= BLE_GAP_ADV_TYPE_ADV_NONCONN_IND;
		m_adv_params.p_peer_addr	= NULL;
		m_adv_params.fp					  = BLE_GAP_ADV_FP_ANY;
		m_adv_params.interval			= NON_CONNECTABLE_ADV_INTERVAL;
		m_adv_params.timeout			= 0;
		m_adv_params.p_whitelist	= NULL;
				
		SEGGER_RTT_printf(0, "channel mode %d\n", channel_mode);
		if(channel_mode == 37)
		{
			ch_mask.ch_37_off				 = 0;
			ch_mask.ch_38_off				 = 1;
			ch_mask.ch_39_off 			 = 1;
			m_adv_params.channel_mask = ch_mask;
		}
		else if(channel_mode == 38)
		{
			ch_mask.ch_37_off				 = 1;
			ch_mask.ch_38_off				 = 0;
			ch_mask.ch_39_off 			 = 1;
			m_adv_params.channel_mask = ch_mask;
		}
		else if(channel_mode == 39)
		{
			ch_mask.ch_37_off				 = 0;
			ch_mask.ch_38_off				 = 1;
			ch_mask.ch_39_off 			 = 1;
			m_adv_params.channel_mask = ch_mask;
		}
}

And my main looks like this:

int main(void)
{
	
    uint32_t err_code;
    // Initialize.
//  APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false); // Comment this when channel switching on
		timers_init(); // init timers
		//gap_params_init();
	
    err_code = bsp_init(BSP_INIT_LED, APP_TIMER_TICKS(100, APP_TIMER_PRESCALER), NULL);
    APP_ERROR_CHECK(err_code);
    ble_stack_init();
		//advertising_init(m_channel_mode); // 		

		err_code = app_timer_start(channel_timer_id, CHANNEL_TIMER_INTERVAL, NULL);
		APP_ERROR_CHECK(err_code);

	// Enter main loop.
    for (;; )
    {
        power_manage();
    }
}

[endnode]

Hello Mathias,

Have you tried "ble_radio_notification" module? That might solve your problem without need to use timers, just alter data and channel through standard SD function calls after every adv. event so it's ready to use different channel (and data) on the very next event and keep time and other management to SoftDevice.

Cheers Jan

Edit 9-March-2017

I've forgotten that there is no SD API function to just alter adv. channel map, this works only for adv./scan rsp. data and device (advertising) address. So the only way how to do it today is to stop/start advertising and that's not possible on radio notification event (to be precise it is but will destroy adv. interval timing). Would be great if Nordic adds such function to SD API in next Soft Device release but hard to say if such feature would be very useful. For the time being either application timer or hacking Soft Device RAM structures (and writing into them directly on radio notification event) is the way forward.

Cheers Jan

[Mathias Vandel]

sorry about that, but i do not have such a check box?

However, I call this in main:

	err_code = ble_radio_notification_init(6, NRF_RADIO_NOTIFICATION_DISTANCE_800US, on_ble_radio_active_evt);
	APP_ERROR_CHECK(err_code);

which works and on_ble_radio_active_evt is triggered correctly, which calls advertising_init just as planned.

In my advertising_init i have this code:

	if(channel_mode == 37)
	{
		SEGGER_RTT_printf(0, "channel_mode == 37 %d \n", channel_mode);
		channel_mode = 38;
		ch_mask.ch_37_off = 0;
		ch_mask.ch_38_off = 1;
		ch_mask.ch_39_off	= 1;
		m_adv_params.channel_mask = ch_mask;
	}
	else if(channel_mode == 38)
	{
		SEGGER_RTT_printf(0, "channel_mode == 38 %d \n", channel_mode);
		channel_mode = 39;
		ch_mask.ch_37_off = 0;
		ch_mask.ch_38_off = 1;
		ch_mask.ch_39_off	= 1;
		m_adv_params.channel_mask = ch_mask;
	}
	else if(channel_mode == 39)
	{
		SEGGER_RTT_printf(0, "channel_mode == 39 %d \n", channel_mode);
		channel_mode = 37;
		ch_mask.ch_37_off = 0;
		ch_mask.ch_38_off = 1;
		ch_mask.ch_39_off	= 1;
		m_adv_params.channel_mask = ch_mask;
	}		

I can see in RTT-viewer that it goes to channel 37 then 38 then 39 then 37 and so on.

But when i look at the packages in wireshark using the sniffer it only advertises on channel 37.

So i thought that i might have to stop the advertising, init the advertising and then advertising_start againg, which i tried as follows:

static void on_ble_radio_active_evt(bool radio_active) {

    if (radio_active) 
			{	
				advertising_stop();
				advertising_init();
				advertising_start();
      }
}

But without any luck.. advertising_stop and advertising_startboth returns NRF_SUCCES..

Got it to work... The problem was that i had the same mask for all possible channels.. Thank you very much for your help :-) Appreciated!