Is it possible to BLE scanning in one channel instead of 3 channel?

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Alan Ajit — Tue, 18 Sep 2018 13:36:28 GMT

Thank you for your support.

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Einar Thorsrud — Tue, 18 Sep 2018 13:30:33 GMT

Yes, something's clearly wrong. You make instance of m_adv_params in your advertising_init() function where you set the channel_mask, but you never actually use this variable anywhere. It cannot have any effect whatsoever, so just remove it.

As you use the advertising module, you need to look at the first parameter of your call to ble_advertising_start(), the which is an instance of ble_advertising_t. This is called m_advertising in most examples. You should instead set something like this in your code before you call ble_advertising_init():

m_advertising.adv_params.channel_mask[4] = 0x80;

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Alan Ajit — Tue, 18 Sep 2018 12:44:05 GMT

This is my function

/**@brief Function for initializing the Advertising functionality.
*/
static void advertising_init(void)
{
ret_code_t err_code;
ble_advertising_init_t init;
ble_gap_adv_params_t m_adv_params;
m_adv_params.channel_mask[4] =0x80;
memset(&init, 0, sizeof(init));

init.advdata.name_type = BLE_ADVDATA_FULL_NAME;
init.advdata.include_appearance = true;
init.advdata.flags = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
init.advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
init.advdata.uuids_complete.p_uuids = m_adv_uuids;

init.config.ble_adv_fast_enabled = true;
init.config.ble_adv_fast_interval = APP_ADV_INTERVAL;
init.config.ble_adv_fast_timeout = APP_ADV_DURATION;
init.evt_handler = on_adv_evt;
// m_adv_params.channel_mask[4] =0x80;

err_code = ble_advertising_init(&m_advertising, &init);
APP_ERROR_CHECK(err_code);

ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}

nothing do additional . is it any wrong?

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Einar Thorsrud — Wed, 12 Sep 2018 10:51:49 GMT

I still find it a bit strange. Can you show me your complete advertising_init() function?

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Alan Ajit — Wed, 12 Sep 2018 08:01:24 GMT

I tested Central peripheral example in SDk 15

I am just modified in scanner side

static ble_gap_scan_params_t const m_scan_params =
{
.active = 1,
.interval = SCAN_INTERVAL,
.window = SCAN_WINDOW,
.timeout = SCAN_DURATION,
.scan_phys = BLE_GAP_PHY_1MBPS,
.filter_policy = BLE_GAP_SCAN_FP_ACCEPT_ALL,
.channel_mask[4] = 0x60, // <- DON'T SCAN ON CHANNEL 37 or 38
};

and modified in advertiser side in advertising_init(void)

ble_gap_adv_params_t m_adv_params;

m_adv_params.channel_mask[4] =0x80;

just two things modified nothing more

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Einar Thorsrud — Wed, 12 Sep 2018 07:52:55 GMT

That's odd. What do you do with m_scan_params m_adv_params after setting the channel mask_field? Can you upload the full source code for the advertise and scanner?

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Alan Ajit — Wed, 12 Sep 2018 07:33:53 GMT

Sorry for late reply

I tested as per above modification

For testing i use two nrf device one as Scanner and other as Advertiser

Scanner:-

Advertiser:- modified in advertising_init(void)

ble_gap_adv_params_t m_adv_params;

m_adv_params.channel_mask[4] =0x80;

modified for Advertising in Channel's 37 and 38 advertising

But i get Advertising in Scanner(scanning only in 39 channel) how its possible?

Is it any mistake in my procedure?

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Einar Thorsrud — Fri, 31 Aug 2018 13:36:48 GMT

You can do like this (modified from this post):

/** @brief Parameters used when scanning. */
static ble_gap_scan_params_t const m_scan_params =
{
    .active             = 1,
    .interval           = SCAN_INTERVAL,
    .window             = SCAN_WINDOW,
    .timeout            = SCAN_DURATION,
    .scan_phys          = BLE_GAP_PHY_1MBPS,
    .filter_policy      = BLE_GAP_SCAN_FP_ACCEPT_ALL,
    .channel_mask[4]    = 0x60, // <- DON'T SCAN ON CHANNEL 37 or 38
};

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Alan Ajit — Fri, 31 Aug 2018 13:24:04 GMT

Thanks i see channel mask in SDK 15.0.0 .

channel mask has 40 bits that is 5 byte LSB for channel index 0 and MSB for channel index 39 if i set channel mask MSB to 0 and next 2 bits set to 1 scanning happens in channel 39 only is it right procedure for scanning one channel?

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Einar Thorsrud — Fri, 31 Aug 2018 09:31:18 GMT

Which SDK and SoftDevice version are you using? The ability to scan on specific channels was added in version SoftDevice version 6.0.0, which is used in SDK 15.0.0. It is not supported if you use an older SoftDevice.

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Alan Ajit — Fri, 31 Aug 2018 09:24:25 GMT

Thanks for your replay but when i check the ble_gap_scan_params_t i can't find channel mask i am using central peripheral example in BLE how i change scanning in one channel only

RE: Is it possible to BLE scanning in one channel instead of 3 channel?

Einar Thorsrud — Fri, 31 Aug 2018 09:09:22 GMT

Hi,

You can scan on only one channel by setting the channel_mask field in the ble_gap_scan_params_t struct that you pass to the call to sd_ble_gap_scan_start().