advertising interval

[roger.k]

Hi. I'm using nRF52832, SDK13.0.0 as peripheral.

I set the values as below to advertise every 400msec.

......

adv_params.type = BLE_GAP_ADV_TYPE_ADV_IND;

adv_params.p_peer_addr = NULL;

adv_params.fp = BLE_GAP_ADV_FP_ANY;

adv_params.interval = 640;

adv_params.timeout = 0;

......

p_encoded_advdata[0] = 0x02; p_encoded_advdata[1] = BLE_GAP_AD_TYPE_FLAGS; p_encoded_advdata[2] = 0x06;

......

p_encoded_rspdata[0] = 0x07; p_encoded_rspdata[1] = 0x08;

......

sd_ble_gap_adv_data_set(p_encoded_advdata, len_advdata, p_encoded_rspdata, len_rspdata);

err_code = sd_ble_gap_adv_start(&adv_params, BLE_CONN_CFG_TAG_DEFAULT);

APP_ERROR_CHECK(err_code);

But as i've test, the interval is not 400msec exactly.

Normally it's 400msec around. But sometimes it's not advertising during few seconds(4~5seconds). At that time, central cannot connect my device. I don't know why.

I need your help.

[endnode]

Standard GAP compliant device which uses certified BLE stack (such as Nordic Soft Device) should add some jitter to advertising interval so it's normal that you see 400ms +- few percent. But if you see longer gaps (e.g. few seconds) then either your scanner cannot run on 100% duty cycle or there is some serious problem on advertiser's FW. Can you test it with simple mobile BLE app like nRF5 Connect for Android or iOS? These typically display row of captured advertising packets and if there are unusual gaps you can spot them easily.

[roger.k]

Thanks a lot. Let me check.

[roger.k]

I have one more question. If central doesn't scan and it tyries to connect to my peripheral's pear address directly, is it possible? I hope your help.

[endnode]

No Roger, that doesn't make sense. There is no connection if there is no ADV_XXX packet (because CONNECT_REQ must be issued on the same channel exactly in 150us after connectable ADV_XXX packet is sent) and if your device isn't scanning it doesn't know when to connect (misses that 150us window).

[roger.k]

Thank you very much for your help.