Can I change nRF5 bluetooth advertising interval dynamically?

RE: Can I change nRF5 bluetooth advertising interval dynamically?

Jarmo — Wed, 18 Jan 2017 15:09:23 GMT

Okay, thank you very much about those hints! I think I can now implement the thing :)

RE: Can I change nRF5 bluetooth advertising interval dynamically?

AmbystomaLabs — Wed, 18 Jan 2017 14:54:43 GMT

Jarmo, We developed our product in SDK11 and there wasn't support for this built in. However, you can do the same thing by just tying the advertising interval to a variable.

So you init like this:

static void advertising_init(uint32_t adv_interval )
{ ...
		m_adv_params.interval = adv_interval;
...}

As Sigurd said you must first stop advertising:

						err_code = sd_ble_gap_adv_stop();
						APP_ERROR_CHECK(err_code);

Then init with whatever period you choose (here it is 3200*.625usec or 2second interval):

						advertising_init(3200);

And finally start advertising:

						err_code = sd_ble_gap_adv_start(&m_adv_params);
						APP_ERROR_CHECK(err_code);

I should caution you that the power requirements to re-init and re-start advertising are substantial. If your coin cell is already mostly depleted the device may well brown out and reboot.

RE: Can I change nRF5 bluetooth advertising interval dynamically?

Sigurd — Wed, 18 Jan 2017 13:25:24 GMT

If you want to go back to fast mode, you have to first temporarily stop the advertising, and then start in fast mode again.

err_code = sd_ble_gap_adv_stop();
err_code = ble_advertising_start(BLE_ADV_MODE_FAST);

RE: Can I change nRF5 bluetooth advertising interval dynamically?

Jarmo — Wed, 18 Jan 2017 12:54:12 GMT

Okay, thanks for that. However, the code from SDK8 doesn't seem to support that.

Also, if I want to get bak from slow mode to fast mode, how to do that?

RE: Can I change nRF5 bluetooth advertising interval dynamically?

Sigurd — Wed, 18 Jan 2017 10:37:59 GMT

Hi,

The advertising module have two different modes you can use for this. ADV_MODE_FAST and ADV_MODE_SLOW, and you can specify the advertising interval you want for each mode. The advertising will start in ADV_MODE_FAST, and switch to ADV_MODE_SLOW after a specified timeout period(APP_ADV_FAST_TIMEOUT_IN_SECONDS). The ADV_MODE_SLOW also has a timeout period, and when expired it will switch to ADV_MODE_IDLE and stop advertising.

ble_adv_modes_config_t options;
memset(&options, 0, sizeof(options));

options.ble_adv_fast_enabled  = true;
options.ble_adv_fast_interval = APP_ADV_FAST_INTERVAL;
options.ble_adv_fast_timeout  = APP_ADV_FAST_TIMEOUT_IN_SECONDS;

options.ble_adv_slow_enabled  = true;
options.ble_adv_slow_interval = APP_ADV_SLOW_INTERVAL;
options.ble_adv_slow_timeout  = APP_ADV_SLOW_TIMEOUT_IN_SECONDS;

With limited discoverable mode(BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE) it is not allowed to advertise longer than the timeout period. But if you don't want the advertising to stop in the ADV_MODE_SLOW mode, you can switch to general discoverable mode(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE), and set the timeout to 0 to do unlimited advertising:

advdata.flags                 = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
options.ble_adv_slow_timeout  = 0;