Setting static random address more than once

[D0023]

Hello,

I am using bt_id_create() to set static random address.

bt_id_create() is called before bt_enable().

This works and sets the device address to a random address I specify.

But how can I change that address? For example - I have everything stopped (no connections, no advertisement), and I call bt_disable(). Then at some point later, I want to re-start BT but with different static random address. How can I do that?

I do not use settings, neither BT privacy. I just need to be able and use different static random address, when I enable BT.

Thank you,

D.

[Hung Bui]

Hi D0023, 

In stead of calling bt_id_create() you can call bt_id_reset() to change the address of the current identity. You would need to stop advertising before changing the address. 

Note that identity BT_ID_DEFAULT (which is 0) is not possible to reset. You can only reset identity >0. 

Please see the following code that I modified from the lbs example. The code will advertise with different addresses every 1 second: 

void main(void)
{
	int blink_status = 0;
	int err;
	struct bt_le_adv_param adv_param = {
		.id = BT_ID_DEFAULT,
		.sid = 0,
		.secondary_max_skip = 0,
		.options = (BT_LE_ADV_OPT_CONNECTABLE),
		.interval_min = 0x0020, /* 20 ms */
		.interval_max = 0x0020, /* 20 ms */
		.peer = NULL,
	};

	printk("Starting Bluetooth Peripheral LBS example\n");

	err = dk_leds_init();
	if (err) {
		printk("LEDs init failed (err %d)\n", err);
		return;
	}

	err = init_button();
	if (err) {
		printk("Button init failed (err %d)\n", err);
		return;
	}

	if (IS_ENABLED(CONFIG_BT_LBS_SECURITY_ENABLED)) {
		err = bt_conn_auth_cb_register(&conn_auth_callbacks);
		if (err) {
			printk("Failed to register authorization callbacks.\n");
			return;
		}

		err = bt_conn_auth_info_cb_register(&conn_auth_info_callbacks);
		if (err) {
			printk("Failed to register authorization info callbacks.\n");
			return;
		}
	}

	err = bt_enable(NULL);
	if (err) {
		printk("Bluetooth init failed (err %d)\n", err);
		return;
	}
	printk("Bluetooth initialized\n");

	if (IS_ENABLED(CONFIG_SETTINGS)) {
		settings_load();
	}
	err = bt_lbs_init(&lbs_callbacs);
	if (err) {
		printk("Failed to init LBS (err:%d)\n", err);
		return;
	}
	adv_param.id=1;
	err = bt_le_adv_start(&adv_param, ad, ARRAY_SIZE(ad),
			      sd, ARRAY_SIZE(sd));
	if (err) {
		printk("Advertising failed to start (err %d)\n", err);
		return;
	}

	printk("Advertising successfully started\n");

	for (;;) {
		dk_set_led(RUN_STATUS_LED, (++blink_status) % 2);
		k_sleep(K_MSEC(RUN_LED_BLINK_INTERVAL));
		bt_le_adv_stop();
		err = bt_id_reset(1,NULL, NULL);
		if (err < 0) {
			printk("Reset ID failed (err %d)\n", err);
		};
		err = bt_le_adv_start(&adv_param, ad, ARRAY_SIZE(ad),
			      sd, ARRAY_SIZE(sd));
		if (err) {
			printk("Advertising failed to start (err %d)\n", err);
		return;
		}
	}
}

Notice how I set the advertising identity to 1 by calling adv_param.id=1; . In the code I set address to NULL to generate random static address, but you can input your own address. 

Also you need to configure CONFIG_BT_ID_MAX=2

[D0023]

Thank you. This clarified my issue.