How to get the attributes from nordic ble from the example of "peripheral_lbs".

[Ashok_Kumar]

Hello All,

I'm tried to interface nordic with "peripheral_lbs" with arduino nano BLE with the example of "Led Control". Arduino nano ble is requesting attributes and nordic is disconnected after 10 seconds.

 

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

#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 <drivers/gpio.h>
#include <soc.h>

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

#include <bluetooth/services/lbs.h>

#include <settings/settings.h>

#include <dk_buttons_and_leds.h>

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


#define RUN_STATUS_LED          DK_LED1
#define CON_STATUS_LED          DK_LED2
#define RUN_LED_BLINK_INTERVAL  1000

#define USER_LED                DK_LED3

#define USER_BUTTON             DK_BTN1_MSK

static bool app_button_state;

static const struct bt_data ad[] = {
	BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
	BT_DATA(BT_DATA_NAME_COMPLETE, DEVICE_NAME, DEVICE_NAME_LEN),
};

static const struct bt_data sd[] = {
	BT_DATA_BYTES(BT_DATA_UUID128_ALL, BT_UUID_LBS_VAL),
};

static void connected(struct bt_conn *conn, uint8_t err)
{
	if (err) {
		printk("Connection failed (err %u)\n", err);
		return;
	}

	printk("Connected\n");

	dk_set_led_on(CON_STATUS_LED);
}

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

	dk_set_led_off(CON_STATUS_LED);
}

#ifdef CONFIG_BT_LBS_SECURITY_ENABLED
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) {
		printk("Security changed: %s level %u\n", addr, level);
	} else {
		printk("Security failed: %s level %u err %d\n", addr, level,
			err);
	}
}
#endif

static struct bt_conn_cb conn_callbacks = {
	.connected        = connected,
	.disconnected     = disconnected,
#ifdef CONFIG_BT_LBS_SECURITY_ENABLED
	.security_changed = security_changed,
#endif
};

#if defined(CONFIG_BT_LBS_SECURITY_ENABLED)
static void auth_passkey_display(struct bt_conn *conn, unsigned int passkey)
{
	char addr[BT_ADDR_LE_STR_LEN];

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

	printk("Passkey for %s: %06u\n", addr, passkey);
}

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 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));

	printk("Pairing completed: %s, bonded: %d\n", 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));

	printk("Pairing failed conn: %s, reason %d\n", addr, reason);
}

static struct bt_conn_auth_cb conn_auth_callbacks = {
	.passkey_display = auth_passkey_display,
	.cancel = auth_cancel,
	.pairing_complete = pairing_complete,
	.pairing_failed = pairing_failed
};
#else
static struct bt_conn_auth_cb conn_auth_callbacks;
#endif

static void app_led_cb(bool led_state)
{
	//dk_set_led(USER_LED, led_state);
        printk("\n----------- led  changed cb -----------\n");
}

static bool app_button_cb(void)
{
        printk("\n----------- button  changed cb -----------\n");
	return app_button_state;
}

static struct bt_lbs_cb lbs_callbacs = {
	.led_cb    = app_led_cb,
	.button_cb = app_button_cb,
};

static void button_changed(uint32_t button_state, uint32_t has_changed)
{
	if (has_changed & USER_BUTTON) {
		uint32_t user_button_state = button_state & USER_BUTTON;

		bt_lbs_send_button_state(user_button_state);
		app_button_state = user_button_state ? true : false;
	}

        printk("----------- button changed function -----------\n");
}

static int init_button(void)
{
	int err;

	err = dk_buttons_init(button_changed);
	if (err) {
		printk("Cannot init buttons (err: %d)\n", err);
	}

	return err;
}

void main(void)
{
	int blink_status = 0;
	int err;

	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;
	//}

	bt_conn_cb_register(&conn_callbacks);
	if (IS_ENABLED(CONFIG_BT_LBS_SECURITY_ENABLED)) {
		bt_conn_auth_cb_register(&conn_auth_callbacks);
	}

	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;
	}

	err = bt_le_adv_start(BT_LE_ADV_CONN, 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");
        
        int i=0;

	for (;;) {
		//dk_set_led(RUN_STATUS_LED, (++blink_status) % 2);
		k_sleep(K_MSEC(RUN_LED_BLINK_INTERVAL));
               
        printk(".");

                

                
	}
}

 

Below code is from arduino 

#include <ArduinoBLE.h>

// variables for button
const int buttonPin = 2;
int oldButtonState = LOW;

void setup() {
  Serial.begin(9600);
  while (!Serial);

  // configure the button pin as input
  pinMode(buttonPin, INPUT);

  Serial.println("Set button as i/p");

  // initialize the Bluetooth® Low Energy hardware
  BLE.begin();

  Serial.println("Bluetooth® Low Energy Central - LED control");

  Serial.println("--------- Start scanning for particular sercive id --> 19b10000-e8f2-537e-4f6c-d104768a1214");
  // start scanning for peripherals
//  BLE.scanForUuid("19b10000-e8f2-537e-4f6c-d104768a1214");        //standard

  BLE.scanForUuid("00001523-1212-efde-1523-785feabcd123");          // nordic led uuid

  //00001525, 0x1212, 0xefde, 0x1523, 0x785feabcd123
}

void loop() {

  Serial.println("Checking peripheral is available or not");
  
  // check if a peripheral has been discovered
  BLEDevice peripheral = BLE.available();

  Serial.print("-------- peripheral = ");
  Serial.print(peripheral);

  if (peripheral) {
    // discovered a peripheral, print out address, local name, and advertised service
    Serial.print("Found and address is  ");
    Serial.println(peripheral.address());
    Serial.print(" ', local name is ");
    Serial.print(peripheral.localName());
    Serial.println("' advertise service uuid is  ");
    Serial.print(peripheral.advertisedServiceUuid());
    Serial.println();

    if (peripheral.localName() != "Nordic_LBS") {
      Serial.println("------Local name is not matched with 'LED'");
      return;
    }

    Serial.println("-----------Stop Scanning ---------------");
    // stop scanning
    BLE.stopScan();
    
    Serial.println("------------- Controlled led is calling --------");
    controlLed(peripheral);

    Serial.println("------------- peripheral disconnected, start scanning again for service id --------");

    // peripheral disconnected, start scanning again
    BLE.scanForUuid("00001523-1212-efde-1523-785feabcd123");
  }
}

void controlLed(BLEDevice peripheral) {
  // connect to the peripheral
  Serial.println("Connecting ...");

  if (peripheral.connect()) {
    Serial.println("Connected");
  } else {
    Serial.println("Failed to connect!");
    return;
  }

  // discover peripheral attributes
  Serial.println("Discovering attributes ...");
  if (peripheral.discoverAttributes()) {
    Serial.println("Attributes discovered");
  } else {
    Serial.println("Attribute discovery failed!");
    peripheral.disconnect();
    return;
  }

  // retrieve the LED characteristic
  BLECharacteristic ledCharacteristic = peripheral.characteristic("00001523-1212-efde-1523-785feabcd123");

  if (!ledCharacteristic) {
    Serial.println("Peripheral does not have LED characteristic!");
    peripheral.disconnect();
    return;
  } else if (!ledCharacteristic.canWrite()) {
    Serial.println("Peripheral does not have a writable LED characteristic!");
    peripheral.disconnect();
    return;
  }

  while (peripheral.connected()) {
    // while the peripheral is connected

    // read the button pin
    int buttonState = digitalRead(buttonPin);

    if (oldButtonState != buttonState) {
      // button changed
      oldButtonState = buttonState;

      if (buttonState) {
        Serial.println("button pressed");

        // button is pressed, write 0x01 to turn the LED on
        ledCharacteristic.writeValue((byte)0x01);

//        {
//          
//          ledCharacteristic.write("hello world");
//
//          if(ledCharacteristic.available()){
//            
//           Serial.print( ledCharacteristic.read());
//            }
//          
//          
//          
//          }



          
      } else {
        Serial.println("button released");

        // button is released, write 0x00 to turn the LED off
        ledCharacteristic.writeValue((byte)0x00);
      }
    }
  }

  Serial.println("Peripheral disconnected");
}

Please help me,

Thanks.

[Hung Bui]

Hi Ashok, 

I'm not familiar with the Arduino platform. However, please be aware that the UUID of the LBS service is different from the LBS characteristic

Here is the service: 00001523-1212-efde-1523-785feabcd123

And here is the LED characteristic: 00001525-1212-efde-1523-785feabcd123

Button characteristic: 00001524-1212-efde-1523-785feabcd123

If you want to acccess the LED characteristic, you need to use the correct UUID. 

[Ashok_Kumar]

Hi Hung Bui,

Thanks for the quick response.

I tried to connect to the peripheral (nordic) with central (arduino nano nrf52840) device using the led characteristics uuid but still i'm unable to access the led characteristics.

 // retrieve the LED characteristic
  BLECharacteristic ledCharacteristic = peripheral.characteristic("00001525-1212-efde-1523-785feabcd123");

Thanks,

Ashok.

[Hung Bui]

Hi Ashok, 
Please try to debug and see what could be wrong here. 
I would suggest to test with the standard example provided by Arduino first before you move ahead. 
You need to make sure you managed to: 
1 - Scan

2 - Connect 

3 - Discover the attribute table  (peripheral.discoverAttributes() )

4 - Access the characteristic. 

You can consider using a sniffer trace to capture what happen over the air to make it easier to debug.