nRF53: how to set the BLE Public MAC Address from the APP core?

[Rokk Research]

Hi,

We have an application running on the nRF53, and would like to change the BLE MAC address from the default Random Static Address, to a Public Address with a valid Vendor OUI.

I tried to use bt_id_create(), but that seems to work only for Random Static Addresses (i.e., with the first 2 MSBits of the MAC Address set to 1). Trying to set an address with the actual Vendor OUI results in: "Only static random identity address supported"

I also tried to use bt_ctlr_set_public_addr(), but that function doesn't appear to be linked into the APP core image.

Is there a straightforward way to set the Public MAC Address from the APP Core, in a way similar to calling bt_id_create()? I found some tickets on DevZone implying that it can be done from the NET Core by sending a message from the APP Core, but that seems overly complicated and they were older tickets (and we're not using the SoftDevice).  Thanks!

[Einar Thorsrud]

Hi,

You can set the address on the app side as well, using bt_id_create(). You can see an example of that in this exercise (here the address is not public, but the method is the same regardless of address type). 

[Rokk Research]

Hi Einar - the problem with using bt_id_create() is that it only works with Random Static Addresses - i.e., ones where the 2 MSBit's of the first octet are set to 1.  A Public MAC Address has the 2 MSBit's set to 0.

i.e., this works:

bt_addr_le_from_str("FF:EE:DD:CC:BB:AA", "random", &addr);
bt_id_create(&addr, NULL);

but this will result in the error "Only static random identity address supported":

bt_addr_le_from_str("3F:EE:DD:CC:BB:AA", "public", &addr);
bt_id_create(&addr, NULL);

[Einar Thorsrud]

Hi,

Yes, you are right. I did not notice this. Honestly public address is not much used, but you can do this via another approach described here and here. This is a modified beacon sample from SDK 2.9 which does it:

/* main.c - Application main entry point */

/*
 * Copyright (c) 2015-2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/types.h>
#include <stddef.h>
#include <zephyr/sys/printk.h>
#include <zephyr/sys/util.h>

#include <zephyr/bluetooth/bluetooth.h>
#include <zephyr/bluetooth/hci.h>

#include <zephyr/settings/settings.h>
#include <sdc_hci_vs.h>


#define DEVICE_NAME CONFIG_BT_DEVICE_NAME
#define DEVICE_NAME_LEN (sizeof(DEVICE_NAME) - 1)

/*
 * Set Advertisement data. Based on the Eddystone specification:
 * https://github.com/google/eddystone/blob/master/protocol-specification.md
 * https://github.com/google/eddystone/tree/master/eddystone-url
 */
static const struct bt_data ad[] = {
	BT_DATA_BYTES(BT_DATA_FLAGS, BT_LE_AD_NO_BREDR),
	BT_DATA_BYTES(BT_DATA_UUID16_ALL, 0xaa, 0xfe),
	BT_DATA_BYTES(BT_DATA_SVC_DATA16,
		      0xaa, 0xfe, /* Eddystone UUID */
		      0x10, /* Eddystone-URL frame type */
		      0x00, /* Calibrated Tx power at 0m */
		      0x00, /* URL Scheme Prefix http://www. */
		      'z', 'e', 'p', 'h', 'y', 'r',
		      'p', 'r', 'o', 'j', 'e', 'c', 't',
		      0x08) /* .org */
};

/* Set Scan Response data */
static const struct bt_data sd[] = {
	BT_DATA(BT_DATA_NAME_COMPLETE, DEVICE_NAME, DEVICE_NAME_LEN),
};

static int set_bd_addr(void)
{
	int err = 0;
	struct net_buf *buf;
	sdc_hci_cmd_vs_zephyr_write_bd_addr_t *cmd_params;

	buf = bt_hci_cmd_create(SDC_HCI_OPCODE_CMD_VS_ZEPHYR_WRITE_BD_ADDR ,
				sizeof(*cmd_params));
	if (!buf) {
		printk("Could not allocate command buffer\n");
		return -ENOMEM;
	}

	cmd_params = net_buf_add(buf, sizeof(*cmd_params));

	cmd_params->bd_addr[0]= 0xCC;
	cmd_params->bd_addr[1]= 0xCC;
	cmd_params->bd_addr[2]= 0xCC;
	cmd_params->bd_addr[3]= 0xCC;
	cmd_params->bd_addr[4]= 0xCC;
	cmd_params->bd_addr[5]= 0xCC;



    printk("bt_hci_cmd_send_sync \n");

	err = bt_hci_cmd_send_sync(SDC_HCI_OPCODE_CMD_VS_ZEPHYR_WRITE_BD_ADDR, buf, NULL);
	printk("err: %d \n",err);
	if (err) {
		printk("err: %d \n",err);
		return err;
	}

	printk("Successfully set bd addr \n");

	return 0;
}

static void bt_ready(int err)
{
	char addr_s[BT_ADDR_LE_STR_LEN];
	bt_addr_le_t addr = {0};
	size_t count = 1;

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

	printk("Bluetooth initialized\n");

	set_bd_addr();

	if (IS_ENABLED(CONFIG_SETTINGS)) {
    		settings_load();
	}

	/* Start advertising */
	err = bt_le_adv_start(BT_LE_ADV_NCONN_IDENTITY, ad, ARRAY_SIZE(ad),
			      sd, ARRAY_SIZE(sd));
	if (err) {
		printk("Advertising failed to start (err %d)\n", err);
		return;
	}


	/* For connectable advertising you would use
	 * bt_le_oob_get_local().  For non-connectable non-identity
	 * advertising an non-resolvable private address is used;
	 * there is no API to retrieve that.
	 */

	bt_id_get(&addr, &count);
	bt_addr_le_to_str(&addr, addr_s, sizeof(addr_s));

	printk("Beacon started, advertising as %s\n", addr_s);
}

int main(void)
{
	int err;

	printk("Starting Beacon Demo\n");

	/* Initialize the Bluetooth Subsystem */
	err = bt_enable(bt_ready);
	if (err) {
		printk("Bluetooth init failed (err %d)\n", err);
	}
	return 0;
}

You also need some additional configs in case settings was not used before:

CONFIG_BT_SETTINGS=y
CONFIG_FLASH=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_FLASH_MAP=y
CONFIG_NVS=y
CONFIG_SETTINGS=y

[LLLWJ]

is ok,thank you for you help.