How to Change data rate to 500kbps/125kbps

[Theja]

I am using nrf connect SDK version 2.0

Here, I have a option to change data rate to 1Mbps and 2Mbps,

I'm thinking by using  "CONFIG_BT_CTLR_PHY_CODED" we can change to 125 or 500 kbps, i'm not sure which one its going use as PHY Data rate?.

(by changing this one I can increase range(LOS) of BLE devices) 

[Amanda Hsieh]

Hi, 

You can take a look at throughput with the settings for BT_CONN_LE_PHY_OPT_CODED_S8 (125kbps) and BT_CONN_LE_PHY_OPT_CODED_S2 (500kbps).

Regards,
Amanda H.

[Theja]

Hi Amanda thanks for the reply,

I'm trying to update the data rate using "bt_conn_le_phy_update" API in connected callback but returning error

"failed to update = -5" like this and its updating 2Mbps as a data rate.

here is a code snippet regarding that

static void connected(struct bt_conn *conn, uint8_t conn_err)
{

	int err;
	char addr[30];
	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	if (conn_err)
	{
		LOG_INF("Failed to connect to %s (%d)", addr, conn_err);

		if (default_conn == conn)
		{
			bt_conn_unref(default_conn);
			default_conn = NULL;

			err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
			if (err)
			{
				LOG_ERR("Scanning failed to start (err %d)",
						err);
			}
		}

		return;
	}

	LOG_INF("Connected: %s", addr);

	#if PHY_UPDATE
	// TODO: need to remove
	err = bt_conn_le_phy_update(&conn, &phy);
	if (err) {
		sprintf(bufff_data, "failed to update = %d\r\n", err);
		send_through_uart(bufff_data);
		// return err;
	}
	#endif

	static struct bt_gatt_exchange_params exchange_params;

	exchange_params.func = exchange_func;
	err = bt_gatt_exchange_mtu(conn, &exchange_params);
	if (err)
	{
		LOG_WRN("MTU exchange failed (err %d)", err);
	}

	err = bt_conn_set_security(conn, BT_SECURITY_L0); // BT_SECURITY_L2  ->  BT_SECURITY_L0
	if (err)
	{
		LOG_WRN("Failed to set security: %d", err);

		gatt_discover(conn);
	}

	// TODO: theja newly added
	gatt_discover(conn);

	err = bt_scan_stop();
	if ((!err) && (err != -EALREADY))
	{
		LOG_ERR("Stop LE scan failed (err %d)", err);
	}
}

static void disconnected(struct bt_conn *conn, uint8_t reason)
{
	char addr[BT_ADDR_LE_STR_LEN];
	int err;

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

	LOG_INF("Disconnected: %s (reason %u)", addr, reason);

	if (default_conn != conn)
	{
		return;
	}

	bt_conn_unref(default_conn);
	default_conn = NULL;

	err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
	if (err)
	{
		LOG_ERR("Scanning failed to start (err %d)",
				err);
	}
}

static void security_changed(struct bt_conn *conn, bt_security_t level,
							 enum bt_security_err err)
{
	char addr[BT_ADDR_LE_STR_LEN];

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

	if (!err)
	{
		LOG_INF("Security changed: %s level %u", addr, level);
	}
	else
	{
		LOG_WRN("Security failed: %s level %u err %d", addr,
				level, err);
	}

	gatt_discover(conn);
}

#if PHY_UPDATE
uint8_t data_buff[50] = {'\0'};
static const char *phy2str(uint8_t phy)
{
	switch (phy) {
	case 0: return "No packets";
	case BT_GAP_LE_PHY_1M: return "LE 1M";
	case BT_GAP_LE_PHY_2M: return "LE 2M";
	case BT_GAP_LE_PHY_CODED: return "LE Coded";
	default: return "Unknown";
	}
}

static void le_phy_updated(struct bt_conn *conn,
			   struct bt_conn_le_phy_info *param)
{
	printk("LE PHY updated: TX PHY %s, RX PHY %s\n",
	       phy2str(param->tx_phy), phy2str(param->rx_phy));

	// TODO: need to remove
	sprintf(data_buff, "LE PHY updated: TX PHY %s, RX PHY %s\n",phy2str(param->tx_phy), phy2str(param->rx_phy));
	send_through_uart(data_buff);
}
#endif

BT_CONN_CB_DEFINE(conn_callbacks) = {
	.connected = connected,
	.disconnected = disconnected,
	.security_changed = security_changed,
	#if PHY_UPDATE
	.le_phy_updated = le_phy_updated
	#endif
	};

I,m trying to change with this parameters

static struct bt_conn_le_phy_param phy = {

    .options = BT_CONN_LE_PHY_OPT_CODED_S2,

    .pref_rx_phy = BT_GAP_LE_PHY_CODED,

    .pref_tx_phy = BT_GAP_LE_PHY_CODED

};

[Amanda Hsieh]

Hi, 

Do you also get <wrn> bt_hci_core: bt_hci_cmd_send_sync: opcode 0x2032 status 0x11 like this post? If so, try in prj.conf:
CONFIG_BT_CTLR_PHY_CODED=y

Does this help?

-Amanda H.

[Theja]

Hi,

I am already included it in prj.cofig file still i'm getting same error?

Amanda Hsieh said:

CONFIG_BT_CTLR_PHY_CODED=

[Amanda Hsieh]

Are you using nRF52833DK or a custom board?

Does the central board support coded phy and updating phy(CONFIG_BT_USER_PHY_UPDATE=y)? What HW does the central board use?

-Amanda H.