How to advertise TX power of a peripheral

[adam_atmo]

Hi,

I am programming the nRF52833 DK using the nRF Connect SDK (v2.00).  I have built and flashed the Bluetooth: Peripheral HT sample from Zephyr to both boards successfully. I use the Android nRF Connect app to connect to the SoC.

I would like to see what the TX power of the peripheral is so that I can confrim that it has been set as desired but I am not sure how to show this information. I have seen that some devices advertise soemthing like: "TX power level: 0dBm". How do I do this? I have attached a PDF file with a screenshot of this.

I have also attached a piece of code that shows the advertising data (taken from Bluetooth: Peripheral HT). I can see in the Zephyr gap.h file that there are numerous flags / data type definitions that can be used as adveritsing data. BT_DATA_TX_POWER is one of these - I tried to use it as shown blow (commented out) but it did not work.

Thanks,

Adam

static const struct bt_data ad[] = {
	BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
	//BT_DATA_BYTES(BT_DATA_TX_POWER), 
	BT_DATA_BYTES(BT_DATA_UUID16_ALL,
		      BT_UUID_16_ENCODE(BT_UUID_HTS_VAL),
		      BT_UUID_16_ENCODE(BT_UUID_DIS_VAL),
		      BT_UUID_16_ENCODE(BT_UUID_BAS_VAL)),
};

tx power data.pdf

[Kenneth]

Hello,

I can find there is a bt_tx_power_adv_data_fill() implementation in bt_tx_power_adv.c that you likely you can use here. I can find that the peripheral_fast_pair example seem to call this from bt_adv_helper_tx_power_prepare(). Basically the bt_tx_power_adv_data_fill() will read out the tx power used in the controller and prepare to be used in advertisment. 

static struct bt_data ad[] = {
	BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
	BT_DATA_BYTES(BT_DATA_UUID16_ALL,
		      BT_UUID_16_ENCODE(BT_UUID_HIDS_VAL),
		      BT_UUID_16_ENCODE(BT_UUID_BAS_VAL)),
	/* Empty placeholder for TX power advertising data. */
	{
	},
	/* Empty placeholder for Fast Pair advertising data. */
	{
	},
};

Best regards,
Kenneth

[adam_atmo]

Thanks Kenneth,

I have included the relevant files/functions from the fast pair sample into the Bluetooth: Peripheral HT sample; however, the applciation is failing to build. I have attached my main.c and prj.conf file. Please let me know if I am using the functions correctly - I have pointed out clearly the changes I have made to the Bluetooth: Peripheral HT sample.

Adam

Fullscreen 7345.main.c Download

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

/*
 * Copyright (c) 2019 Aaron Tsui <[email protected]>
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/types.h>
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include <sys/printk.h>
#include <sys/byteorder.h>
#include <zephyr.h>

#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/conn.h>
#include <bluetooth/uuid.h>
#include <bluetooth/gatt.h>
#include <bluetooth/services/bas.h>

#include "hts.h"
#include "bt_tx_power_adv.h"

// Taken from fast pair example
#include <logging/log.h>
//LOG_MODULE_DECLARE(fp_sample, LOG_LEVEL_INF);

#define TX_POWER_ADV_DATA_POS	(ARRAY_SIZE(ad) - 2)
//



// Took away const
static struct bt_data ad[] = {
	BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
	BT_DATA_BYTES(BT_DATA_UUID16_ALL,
		      BT_UUID_16_ENCODE(BT_UUID_HTS_VAL),
		      BT_UUID_16_ENCODE(BT_UUID_DIS_VAL),
		      BT_UUID_16_ENCODE(BT_UUID_BAS_VAL)),
	/* Empty placeholder for TX power advertising data. */
	{
	},
	/* Empty placeholder for Fast Pair advertising data. */
	{
	},
};

static void connected(struct bt_conn *conn, uint8_t err)
{
	if (err) {
		printk("Connection failed (err 0x%02x)\n", err);
	} else {
		printk("Connected\n");
	}
}

static void disconnected(struct bt_conn *conn, uint8_t reason)
{
	printk("Disconnected (reason 0x%02x)\n", reason);
}

BT_CONN_CB_DEFINE(conn_callbacks) = {
	.connected = connected,
	.disconnected = disconnected,
};


//Added from fast pair sample
static int bt_adv_helper_tx_power_prepare(struct bt_data *adv_data)
{
	/* Make sure that TX power data was freed and set to NULL to prevent memory leaks. */
	if (adv_data->data) {
		k_free((void *)adv_data->data);
		adv_data->data = NULL;
	}

	size_t buf_size = bt_tx_power_adv_data_size();
	uint8_t *buf = k_malloc(buf_size);

	if (!buf) {
		return -ENOMEM;
	}

	int err = bt_tx_power_adv_data_fill(adv_data, buf, buf_size);

	if (err) {
		k_free(buf);
	}

	return err;
}
/////




static void bt_ready(void)
{
	int err;

	printk("Bluetooth initialized\n");

	hts_init();

	// Added from fast pair example
	err = bt_adv_helper_tx_power_prepare(&ad[TX_POWER_ADV_DATA_POS]);
	if (err) {
		LOG_ERR("Cannot prepare TX power advertising data (err: %d)", err);
		return err;
	}
	///////

	err = bt_le_adv_start(BT_LE_ADV_CONN_NAME, ad, ARRAY_SIZE(ad), NULL, 0);
	if (err) {
		printk("Advertising failed to start (err %d)\n", err);
		return;
	}

	printk("Advertising successfully started\n");
}

static void auth_cancel(struct bt_conn *conn)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	printk("Pairing cancelled: %s\n", addr);
}

static struct bt_conn_auth_cb auth_cb_display = {
	.cancel = auth_cancel,
};

static void bas_notify(void)
{
	uint8_t battery_level = bt_bas_get_battery_level();

	battery_level--;

	if (!battery_level) {
		battery_level = 100U;
	}

	bt_bas_set_battery_level(battery_level);
}

void main(void)
{
	int err;

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

	bt_ready();

	bt_conn_auth_cb_register(&auth_cb_display);

	/* Implement indicate. At the moment there is no suitable way
	 * of starting delayed work so we do it here
	 */
	while (1) {
		k_sleep(K_SECONDS(1));

		/* Temperature measurements simulation */
		hts_indicate();

		/* Battery level simulation */
		bas_notify();
	}
}

CONFIG_BT=y
CONFIG_BT_DEBUG_LOG=y
CONFIG_BT_SMP=y
CONFIG_BT_PERIPHERAL=y
CONFIG_BT_DIS=y
CONFIG_BT_DIS_PNP=y
CONFIG_BT_BAS=y
CONFIG_BT_DEVICE_NAME="Zephyr Health Thermometer"
CONFIG_BT_DEVICE_APPEARANCE=768
CONFIG_BT_ATT_ENFORCE_FLOW=n
CONFIG_CBPRINTF_FP_SUPPORT=y

CONFIG_BT_CTLR_TX_PWR_DYNAMIC_CONTROL=y

[Kenneth]

Try the attachment. Made with NCS v2.

peripheral_ht_adve_tx_power.zip

Kenneth

[adam_atmo]

That works! Thanks Kenneth.