add coded phy feature in Central Uart NCS

[Muhammad Usman]

HI DevZone,

I am trying to add the coded phy features in Peripheral_Uart  and Central_Uart examples of NCS. I hope Coded phy features are successfully added into Peripheral_Uart because i am seeing the Coded Phy LE packet on Wireshark.And got the following output as well on Uart.

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*** Booting Zephyr OS build v3.0.99-ncs1-1· ***<CR><LF>

Starting Nordic UART service example<CR><LF>

Bluetooth initialized<CR><LF>

Created adv: 0x20001f58<CR><LF>

Advertiser 0x20001f58 set started<CR><LF>

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

*** Booting Zephyr OS build v3.0.99-ncs1-1  ***<CR><LF>

Starting Nordic UART service example<CR><LF>

Bluetooth initialized<CR><LF>

Created adv: 0x20001f58<CR><LF>

Advertiser 0x20001f58 set started<CR><LF>

Now issue I am facing an issue with the Central_Uart . When I debug the issue I got the following output.

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00:00:06.[00:00:06.411,468] \033[0m<inf> fs_nvs: alloc wra: 0, ed0\033[0m

[00:00:06.411,499] \033[0m<inf> fs_nvs: data wra: 0, 1d8\033[0m

[00:00:06.411,682] \033[0m<inf> sdc_hci_driver: SoftDevice Controller build revision:

33 78 2a 18 20 f5 61 61 a6 8b 77 60 62 83 39 2a |3x*. .aa ..w`b.9*

7c f1 14 e4 ||... \033[0m

[00:00:06.416,717] \033[0m<inf> bt_hci_core: HW Platform: Nordic Semiconductor (0x0002)\033[0m

[00:00:06.416,748] \033[0m<inf> bt_hci_core: HW Variant: nRF52x (0x0002)\033[0m

[00:00:06.416,778] \033[0m<inf> bt_hci_core: Firmware: Standard Bluetooth controller (0x00) Version 51.10872 Build 1643454488\033[0m

[00:00:06.417,572] \033[0m<inf> bt_hci_core: No ID address. App must call settings_load()\033[0m

[00:00:18.831,848] \033[0m<inf> central_uart: Bluetooth initialized\033[0m

[00:00:18.833,435] \033[0m<inf> bt_hci_core: Identity: E8:2B:FD:17:14:C2 (random)\033[0m

[00:00:18.833,435] \033[0m<inf> bt_hci_core: HCI: version 5.3 (0x0c) revision 0x1136, manufacturer 0x0059\033[0m

[00:00:18.833,465] \033[0m<inf> bt_hci_core: LMP: version 5.3 (0x0c) subver 0x1136\033[0m

[00:00:21.678,649] \033[0m<inf> central_uart: NUS Client module initialized\033[0m

[00:00:26.868,499] \033[1;31m<err> mpsl_init: MPSL ASSERT: 112, 2114\033[0m

[00:00:39.748,535] \033[1;31m<err> os: ***** HARD FAULT *****\033[0m

[00:00:39.748,535] \033[1;31m<err> os: Fault escalation (see below)\033[0m

[00:00:39.748,565] \033[1;31m<err> os: ARCH_EXCEPT with reason 3

\033[0m

[00:00:39.748,565] \033[1;31m<err> os: r0/a1: 0x00000003 r1/a2: 0x0000000d r2/a3: 0x0000000c\033[0m

[00:00:39.748,596] \033[1;31m<err> os: r3/a4: 0x20001c88 r12/ip: 0x00000000 r14/lr: 0x0001b3a1\033[0m

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

00:00:06.[00:00:06.411,468] \033[0m<inf> fs_nvs: alloc wra: 0, ed0\033[0m
[00:00:06.411,499] \033[0m<inf> fs_nvs: data wra: 0, 1d8\033[0m
[00:00:06.411,682] \033[0m<inf> sdc_hci_driver: SoftDevice Controller build revision: 
                                         33 78 2a 18 20 f5 61 61  a6 8b 77 60 62 83 39 2a |3x*. .aa ..w`b.9*
                                         7c f1 14 e4                                      ||...             \033[0m
[00:00:06.416,717] \033[0m<inf> bt_hci_core: HW Platform: Nordic Semiconductor (0x0002)\033[0m
[00:00:06.416,748] \033[0m<inf> bt_hci_core: HW Variant: nRF52x (0x0002)\033[0m
[00:00:06.416,778] \033[0m<inf> bt_hci_core: Firmware: Standard Bluetooth controller (0x00) Version 51.10872 Build 1643454488\033[0m
[00:00:06.417,572] \033[0m<inf> bt_hci_core: No ID address. App must call settings_load()\033[0m
[00:00:18.831,848] \033[0m<inf> central_uart: Bluetooth initialized\033[0m
[00:00:18.833,435] \033[0m<inf> bt_hci_core: Identity: E8:2B:FD:17:14:C2 (random)\033[0m
[00:00:18.833,435] \033[0m<inf> bt_hci_core: HCI: version 5.3 (0x0c) revision 0x1136, manufacturer 0x0059\033[0m
[00:00:18.833,465] \033[0m<inf> bt_hci_core: LMP: version 5.3 (0x0c) subver 0x1136\033[0m
[00:00:21.678,649] \033[0m<inf> central_uart: NUS Client module initialized\033[0m
[00:00:26.868,499] \033[1;31m<err> mpsl_init: MPSL ASSERT: 112, 2114\033[0m
[00:00:39.748,535] \033[1;31m<err> os: ***** HARD FAULT *****\033[0m
[00:00:39.748,535] \033[1;31m<err> os:   Fault escalation (see below)\033[0m
[00:00:39.748,565] \033[1;31m<err> os: ARCH_EXCEPT with reason 3
\033[0m
[00:00:39.748,565] \033[1;31m<err> os: r0/a1:  0x00000003  r1/a2:  0x0000000d  r2/a3:  0x0000000c\033[0m
[00:00:39.748,596] \033[1;31m<err> os: r3/a4:  0x20001c88 r12/ip:  0x00000000 r14/lr:  0x0001b3a1\033[0m
[00:00:39.748,596] \033[1;31m<err> os:  xpsr:  0x61000018\033[0m
[00:00:39.748,626] \033[1;31m<err> os: Faulting instruction address (r15/pc): 0x00034d14\033[0m
[00:00:39.748,657] \033[1;31m<err> os: >>> ZEPHYR FATAL ERROR 3: Kernel oops on CPU 0\033[0m
[00:00:39.748,657] \033[1;31m<err> os: Fault during interrupt handling
\033[0m
[00:00:39.748,687] \033[1;31m<err> os: Current thread: 0x20002668 (main)\033[0m
[00:00:40.592,224] \033[1;31m<err> fatal_error: Resetting system\033[0m
[00:00:00.010,284] \033[0m<inf> fs_nvs: 6 Sectors of 4096 bytes\033[0m
[00:00:00.010,284] \033[0m<inf> fs_nvs: alloc wra: 0, ed0\033[0m
[00:00:00.010,314] \033[0m<inf> fs_nvs: data wra: 0, 1d8\033[0m
[00:00:00.010,498] \033[0m<inf> sdc_hci_driver: SoftDevice Controller build revision: 
                                         33 78 2a 18 20 f5 61 61  a6 8b 77 60 62 83 39 2a |3x*. .aa ..w`b.9*
                                         7c f1 14 e4                                      ||...             \033[0m
[00:00:00.015,533] \033[0m<inf> bt_hci_core: HW Platform: Nordic Semiconductor (0x0002)\033[0m
[00:00:00.015,563] \033[0m<inf> bt_hci_core: HW Variant: nRF52x (0x0002)\033[0m
[00:00:00.015,594] \033[0m<inf> bt_hci_core: Firmware: Standard Bluetooth controller (0x00) Version 51.10872 Build 1643454488\033[0m
[00:00:00.016,387] \033[0m<inf> bt_hci_core: No ID address. App must call settings_load()\033[0m
[00:00:00.016,387] \033[0m<inf> central_uart: Bluetooth initialized\033[0m
[00:00:00.017,974] \033[0m<inf> bt_hci_core: Identity: E8:2B:FD:17:14:C2 (random)\033[0m
[00:00:00.018,005] \033[0m<inf> bt_hci_core: HCI: version 5.3 (0x0c) revision 0x1136, manufacturer 0x0059\033[0m
[00:00:00.018,005] \033[0m<inf> bt_hci_core: LMP: version 5.3 (0x0c) subver 0x1136\033[0m
[00:00:00.019,348] \033[0m<inf> central_uart: NUS Client module initialized\033[0m
[00:00:00.026,458] \033[0m<inf> central_uart: Scanning successfully started\033[0m

I am also inserting my main.c code.

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/*

* Copyright (c) 2018 Nordic Semiconductor ASA

*

* SPDX-License-Identifier: LicenseRef-Nordic-5-Clause

*/

/** @file

* @brief Nordic UART Service Client sample

*/

#include <errno.h>

#include <zephyr/kernel.h>

#include <zephyr/device.h>

#include <zephyr/devicetree.h>

#include <zephyr/sys/byteorder.h>

#include <zephyr/sys/printk.h>

#include <zephyr/bluetooth/bluetooth.h>

#include <zephyr/bluetooth/hci.h>

#include <zephyr/bluetooth/conn.h>

#include <zephyr/bluetooth/uuid.h>

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

/*
 * Copyright (c) 2018 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 */

/** @file
 *  @brief Nordic UART Service Client sample
 */

#include <errno.h>
#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/devicetree.h>
#include <zephyr/sys/byteorder.h>
#include <zephyr/sys/printk.h>

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

#include <bluetooth/services/nus.h>
#include <bluetooth/services/nus_client.h>
#include <bluetooth/gatt_dm.h>
#include <bluetooth/scan.h>

#include <zephyr/settings/settings.h>

#include <zephyr/drivers/uart.h>

#include <zephyr/logging/log.h>

#define LOG_MODULE_NAME central_uart
LOG_MODULE_REGISTER(LOG_MODULE_NAME);

/* UART payload buffer element size. */
#define UART_BUF_SIZE 20

#define KEY_PASSKEY_ACCEPT DK_BTN1_MSK
#define KEY_PASSKEY_REJECT DK_BTN2_MSK

#define NUS_WRITE_TIMEOUT K_MSEC(150)
#define UART_WAIT_FOR_BUF_DELAY K_MSEC(50)
#define UART_RX_TIMEOUT 50

static const struct device *uart = DEVICE_DT_GET(DT_NODELABEL(uart0));
static struct k_work_delayable uart_work;

K_SEM_DEFINE(nus_write_sem, 0, 1);

struct uart_data_t {
	void *fifo_reserved;
	uint8_t  data[UART_BUF_SIZE];
	uint16_t len;
};

static K_FIFO_DEFINE(fifo_uart_tx_data);
static K_FIFO_DEFINE(fifo_uart_rx_data);

static struct bt_conn *default_conn;
static struct bt_nus_client nus_client;

static void ble_data_sent(struct bt_nus_client *nus, uint8_t err,
					const uint8_t *const data, uint16_t len)
{
	ARG_UNUSED(nus);

	struct uart_data_t *buf;

	/* Retrieve buffer context. */
	buf = CONTAINER_OF(data, struct uart_data_t, data);
	k_free(buf);

	k_sem_give(&nus_write_sem);

	if (err) {
		LOG_WRN("ATT error code: 0x%02X", err);
	}
}

static uint8_t ble_data_received(struct bt_nus_client *nus,
						const uint8_t *data, uint16_t len)
{
	ARG_UNUSED(nus);

	int err;

	for (uint16_t pos = 0; pos != len;) {
		struct uart_data_t *tx = k_malloc(sizeof(*tx));

		if (!tx) {
			LOG_WRN("Not able to allocate UART send data buffer");
			return BT_GATT_ITER_CONTINUE;
		}

		/* Keep the last byte of TX buffer for potential LF char. */
		size_t tx_data_size = sizeof(tx->data) - 1;

		if ((len - pos) > tx_data_size) {
			tx->len = tx_data_size;
		} else {
			tx->len = (len - pos);
		}

		memcpy(tx->data, &data[pos], tx->len);

		pos += tx->len;

		/* Append the LF character when the CR character triggered
		 * transmission from the peer.
		 */
		if ((pos == len) && (data[len - 1] == '\r')) {
			tx->data[tx->len] = '\n';
			tx->len++;
		}

		err = uart_tx(uart, tx->data, tx->len, SYS_FOREVER_MS);
		if (err) {
			k_fifo_put(&fifo_uart_tx_data, tx);
		}
	}

	return BT_GATT_ITER_CONTINUE;
}

static void uart_cb(const struct device *dev, struct uart_event *evt, void *user_data)
{
	ARG_UNUSED(dev);

	static size_t aborted_len;
	struct uart_data_t *buf;
	static uint8_t *aborted_buf;
	static bool disable_req;

	switch (evt->type) {
	case UART_TX_DONE:
		LOG_DBG("UART_TX_DONE");
		if ((evt->data.tx.len == 0) ||
		    (!evt->data.tx.buf)) {
			return;
		}

		if (aborted_buf) {
			buf = CONTAINER_OF(aborted_buf, struct uart_data_t,
					   data);
			aborted_buf = NULL;
			aborted_len = 0;
		} else {
			buf = CONTAINER_OF(evt->data.tx.buf,
					   struct uart_data_t,
					   data);
		}

		k_free(buf);

		buf = k_fifo_get(&fifo_uart_tx_data, K_NO_WAIT);
		if (!buf) {
			return;
		}

		if (uart_tx(uart, buf->data, buf->len, SYS_FOREVER_MS)) {
			LOG_WRN("Failed to send data over UART");
		}

		break;

	case UART_RX_RDY:
		LOG_DBG("UART_RX_RDY");
		buf = CONTAINER_OF(evt->data.rx.buf, struct uart_data_t, data);
		buf->len += evt->data.rx.len;

		if (disable_req) {
			return;
		}

		if ((evt->data.rx.buf[buf->len - 1] == '\n') ||
		    (evt->data.rx.buf[buf->len - 1] == '\r')) {
			disable_req = true;
			uart_rx_disable(uart);
		}

		break;

	case UART_RX_DISABLED:
		LOG_DBG("UART_RX_DISABLED");
		disable_req = false;

		buf = k_malloc(sizeof(*buf));
		if (buf) {
			buf->len = 0;
		} else {
			LOG_WRN("Not able to allocate UART receive buffer");
			k_work_reschedule(&uart_work, UART_WAIT_FOR_BUF_DELAY);
			return;
		}

		uart_rx_enable(uart, buf->data, sizeof(buf->data),
			       UART_RX_TIMEOUT);

		break;

	case UART_RX_BUF_REQUEST:
		LOG_DBG("UART_RX_BUF_REQUEST");
		buf = k_malloc(sizeof(*buf));
		if (buf) {
			buf->len = 0;
			uart_rx_buf_rsp(uart, buf->data, sizeof(buf->data));
		} else {
			LOG_WRN("Not able to allocate UART receive buffer");
		}

		break;

	case UART_RX_BUF_RELEASED:
		LOG_DBG("UART_RX_BUF_RELEASED");
		buf = CONTAINER_OF(evt->data.rx_buf.buf, struct uart_data_t,
				   data);

		if (buf->len > 0) {
			k_fifo_put(&fifo_uart_rx_data, buf);
		} else {
			k_free(buf);
		}

		break;

	case UART_TX_ABORTED:
		LOG_DBG("UART_TX_ABORTED");
		if (!aborted_buf) {
			aborted_buf = (uint8_t *)evt->data.tx.buf;
		}

		aborted_len += evt->data.tx.len;
		buf = CONTAINER_OF(aborted_buf, struct uart_data_t,
				   data);

		uart_tx(uart, &buf->data[aborted_len],
			buf->len - aborted_len, SYS_FOREVER_MS);

		break;

	default:
		break;
	}
}

static void uart_work_handler(struct k_work *item)
{
	struct uart_data_t *buf;

	buf = k_malloc(sizeof(*buf));
	if (buf) {
		buf->len = 0;
	} else {
		LOG_WRN("Not able to allocate UART receive buffer");
		k_work_reschedule(&uart_work, UART_WAIT_FOR_BUF_DELAY);
		return;
	}

	uart_rx_enable(uart, buf->data, sizeof(buf->data), UART_RX_TIMEOUT);
}

static int uart_init(void)
{
	int err;
	struct uart_data_t *rx;

	if (!device_is_ready(uart)) {
		LOG_ERR("UART device not ready");
		return -ENODEV;
	}

	rx = k_malloc(sizeof(*rx));
	if (rx) {
		rx->len = 0;
	} else {
		return -ENOMEM;
	}

	k_work_init_delayable(&uart_work, uart_work_handler);

	err = uart_callback_set(uart, uart_cb, NULL);
	if (err) {
		return err;
	}

	return uart_rx_enable(uart, rx->data, sizeof(rx->data),
			      UART_RX_TIMEOUT);
}

static void discovery_complete(struct bt_gatt_dm *dm,
			       void *context)
{
	struct bt_nus_client *nus = context;
	LOG_INF("Service discovery completed");

	bt_gatt_dm_data_print(dm);

	bt_nus_handles_assign(dm, nus);
	bt_nus_subscribe_receive(nus);

	bt_gatt_dm_data_release(dm);
}

static void discovery_service_not_found(struct bt_conn *conn,
					void *context)
{
	LOG_INF("Service not found");
}

static void discovery_error(struct bt_conn *conn,
			    int err,
			    void *context)
{
	LOG_WRN("Error while discovering GATT database: (%d)", err);
}

struct bt_gatt_dm_cb discovery_cb = {
	.completed         = discovery_complete,
	.service_not_found = discovery_service_not_found,
	.error_found       = discovery_error,
};

static void gatt_discover(struct bt_conn *conn)
{
	int err;

	if (conn != default_conn) {
		return;
	}

	err = bt_gatt_dm_start(conn,
			       BT_UUID_NUS_SERVICE,
			       &discovery_cb,
			       &nus_client);
	if (err) {
		LOG_ERR("could not start the discovery procedure, error "
			"code: %d", err);
	}
}

static void exchange_func(struct bt_conn *conn, uint8_t err, struct bt_gatt_exchange_params *params)
{
	if (!err) {
		LOG_INF("MTU exchange done");
	} else {
		LOG_WRN("MTU exchange failed (err %" PRIu8 ")", err);
	}
}

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

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

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

	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_L2);
	if (err) {
		LOG_WRN("Failed to set security: %d", err);

		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)", log_strdup(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", log_strdup(addr),
			level);
	} else {
		LOG_WRN("Security failed: %s level %u err %d", log_strdup(addr),
			level, err);
	}

	gatt_discover(conn);
}

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

static void scan_filter_match(struct bt_scan_device_info *device_info,
			      struct bt_scan_filter_match *filter_match,
			      bool connectable)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(device_info->recv_info->addr, addr, sizeof(addr));

	LOG_INF("Filters matched. Address: %s connectable: %d",
		log_strdup(addr), connectable);
}

static void scan_connecting_error(struct bt_scan_device_info *device_info)
{
	LOG_WRN("Connecting failed");
}

static void scan_connecting(struct bt_scan_device_info *device_info,
			    struct bt_conn *conn)
{
	default_conn = bt_conn_ref(conn);
}

static int nus_client_init(void)
{
	int err;
	struct bt_nus_client_init_param init = {
		.cb = {
			.received = ble_data_received,
			.sent = ble_data_sent,
		}
	};

	err = bt_nus_client_init(&nus_client, &init);
	if (err) {
		LOG_ERR("NUS Client initialization failed (err %d)", err);
		return err;
	}

	LOG_INF("NUS Client module initialized");
	return err;
}

BT_SCAN_CB_INIT(scan_cb, scan_filter_match, NULL,
		scan_connecting_error, scan_connecting);


static void scan_init(void)
{
	int err;

	/* Use active scanning and disable duplicate filtering to handle any
	 * devices that might update their advertising data at runtime. */
	struct bt_le_scan_param scan_param = {
		.type     = BT_LE_SCAN_TYPE_ACTIVE,
		.interval = BT_GAP_SCAN_FAST_INTERVAL,
		.window   = BT_GAP_SCAN_FAST_WINDOW,
		.options  = BT_LE_SCAN_OPT_CODED | BT_LE_SCAN_OPT_NO_1M
	};

	struct bt_scan_init_param scan_init = {
		.connect_if_match = 0,
		.scan_param = &scan_param,
		.conn_param = NULL
	};

	bt_scan_init(&scan_init);
	bt_scan_cb_register(&scan_cb);

	err = bt_scan_filter_add(BT_SCAN_FILTER_TYPE_UUID, BT_UUID_NUS_SERVICE);
	if (err) {
		printk("Scanning filters cannot be set (err %d)\n", err);

		return;
	}

	err = bt_scan_filter_enable(BT_SCAN_UUID_FILTER, false);
	if (err) {
		printk("Filters cannot be turned on (err %d)\n", err);
	}
}

/*
static int scan_init(void)
{
	int err;
	struct bt_scan_init_param scan_init = {
		.connect_if_match = 1,
	};

	bt_scan_init(&scan_init);
	bt_scan_cb_register(&scan_cb);

	err = bt_scan_filter_add(BT_SCAN_FILTER_TYPE_UUID, BT_UUID_NUS_SERVICE);
	if (err) {
		LOG_ERR("Scanning filters cannot be set (err %d)", err);
		return err;
	}

	err = bt_scan_filter_enable(BT_SCAN_UUID_FILTER, false);
	if (err) {
		LOG_ERR("Filters cannot be turned on (err %d)", err);
		return err;
	}

	LOG_INF("Scan module initialized");
	return err;
}

*/

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));

	LOG_INF("Pairing cancelled: %s", log_strdup(addr));
}


static void pairing_complete(struct bt_conn *conn, bool bonded)
{
	char addr[BT_ADDR_LE_STR_LEN];

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

	LOG_INF("Pairing completed: %s, bonded: %d", log_strdup(addr),
		bonded);
}


static void pairing_failed(struct bt_conn *conn, enum bt_security_err reason)
{
	char addr[BT_ADDR_LE_STR_LEN];

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

	LOG_WRN("Pairing failed conn: %s, reason %d", log_strdup(addr),
		reason);
}

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

static struct bt_conn_auth_info_cb conn_auth_info_callbacks = {
	.pairing_complete = pairing_complete,
	.pairing_failed = pairing_failed
};

void main(void)
{
	int err;

	err = bt_conn_auth_cb_register(&conn_auth_callbacks);
	if (err) {
		LOG_ERR("Failed to register authorization callbacks.");
		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) {
		LOG_ERR("Bluetooth init failed (err %d)", err);
		return;
	}
	LOG_INF("Bluetooth initialized");

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

	int (*module_init[])(void) = {uart_init, scan_init, nus_client_init};
	for (size_t i = 0; i < ARRAY_SIZE(module_init); i++) {
		err = (*module_init[i])();
		if (err) {
			return;
		}
	}

	printk("Starting Bluetooth Central UART example\n");


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

	for (;;) {
		/* Wait indefinitely for data to be sent over Bluetooth */
		struct uart_data_t *buf = k_fifo_get(&fifo_uart_rx_data,
						     K_FOREVER);

		err = bt_nus_client_send(&nus_client, buf->data, buf->len);
		if (err) {
			LOG_WRN("Failed to send data over BLE connection"
				"(err %d)", err);
		}

		err = k_sem_take(&nus_write_sem, NUS_WRITE_TIMEOUT);
		if (err) {
			LOG_WRN("NUS send timeout");
		}
	}
}

I also added 

CONFIG_BT_CTLR_PHY_CODED=y

CONFIG_BT_EXT_ADV=y

CONFIG_BT_USER_PHY_UPDATE=y

CONFIG_BT_MAX_CONN=1

in prj.conf file .

I followed the following link. 

devzone.nordicsemi.com/.../326776

But still i am unable to connect the two devices on CODED Phy

Can you please help me with where is the issue? 

Thanks & Regards,

Muhammad Usman