Bluetooh section updated (#1804)

* Bluetooh section updated

* Update content/hardware/06.nicla/boards/nicla-voice/tutorials/user-manual/content.md

Co-authored-by: Josefine Hansson <66409231+jhansson-ard@users.noreply.github.com>

* Bulild-in typo fixed

Bulild-in typo fixed

---------

Co-authored-by: Josefine Hansson <66409231+jhansson-ard@users.noreply.github.com>

Author: jcarolinares

content/hardware/06.nicla/boards/nicla-voice/tutorials/user-manual/assets/user-manual-bt.png

@@ -1325,122 +1325,130 @@ Serial1.println("Hello world!");
 
 ### Bluetooth® Low Energy
 
-To enable Bluetooth® Low Energy communication on the Nicla Voice, you can use the [ArduinoBLE library](https://www.arduino.cc/reference/en/libraries/arduinoble/). The library works with the Nicla Voice with some minor modifications. 
-
-To get started with the ArduinoBLE library and the Nicla Voice, follow these steps:
-
-Include the `Nicla System` header:
-
-```arduino
-#include "Nicla_System.h" 
-```
-
-In the `setup()` function, call `nicla::begin()` to initialize the Nicla Voice board:
-
-```arduino
-void setup() {
-  nicla::begin();
-}
-```
+To enable Bluetooth® Low Energy communication on the Nicla Voice, you can use the [ArduinoBLE library](https://www.arduino.cc/reference/en/libraries/arduinoble/).
 
 Here is an example of how to use the ArduinoBLE library to create a voltage level monitor application:
 
 ```arduino
 #include "Nicla_System.h"
 #include <ArduinoBLE.h>
 
+
 // Define the voltage service and its characteristic
 BLEService voltageService("1101");
 BLEUnsignedCharCharacteristic voltageLevelChar("2101", BLERead | BLENotify);
 
+
 const int analogPin = A0;
 
+
 /**
-  Read voltage level from an analog input of the Nicla Voice,
-  then maps the voltage reading to a percentage value ranging from 0 to 100.
+ Read voltage level from an analog input of the Nicla Voice,
+ then maps the voltage reading to a percentage value ranging from 0 to 100.
+
 
-  @param none
-  @return the voltage level percentage (int).
+ @param none
+ @return the voltage level percentage (int).
 */
 int readVoltageLevel() {
-  int voltage = analogRead(analogPin);
-  int voltageLevel = map(voltage, 0, 1023, 0, 100);
-  return voltageLevel;
+ int voltage = analogRead(analogPin);
+ int voltageLevel = map(voltage, 0, 1023, 0, 100);
+ return voltageLevel;
 }
 
+
 void setup() {
-  // Initialize the Nicla system and the built-in RGB LED
-  nicla::begin();
-  nicla::leds.begin();
+ // Initialize the Nicla system and the built-in RGB LED
+ nicla::begin();
+ nicla::leds.begin();
 
-  Serial.begin(9600);
-  // Wait for the serial connection to be established
-  while (!Serial)
-    ;
 
-  // Initialize the BLE module
-  if (!BLE.begin()) {
-    Serial.println("starting BLE failed!");
-    while (1)
-      ;
-  }
+ Serial.begin(9600);
+ // Wait for the serial connection to be established
+ while (!Serial)
+   ;
 
-  // Set the local name and advertised service for the BLE module
-  BLE.setLocalName("VoltageMonitor");
-  BLE.setAdvertisedService(voltageService);
-  voltageService.addCharacteristic(voltageLevelChar);
-  BLE.addService(voltageService);
 
-  // Start advertising the BLE service
-  BLE.advertise();
-  Serial.println("- Bluetooth device active, waiting for connections...");
+ // Initialize the BLE module
+ if (!BLE.begin()) {
+   Serial.println("starting BLE failed!");
+   while (1)
+     ;
+ }
+
+
+ // Set the local name and advertised service for the BLE module
+ BLE.setLocalName("VoltageMonitor");
+ BLE.setAdvertisedService(voltageService);
+ voltageService.addCharacteristic(voltageLevelChar);
+ BLE.addService(voltageService);
+
+
+ // Start advertising the BLE service
+ BLE.advertise();
+ Serial.println("- Bluetooth device active, waiting for connections...");
 }
 
+
 void loop() {
-  // Check for incoming BLE connections
-  BLEDevice central = BLE.central();
+ // Check for incoming BLE connections
+ BLEDevice central = BLE.central();
 
-  // If a central device is connected
-  if (central) {
-    Serial.print("- Connected to central: ");
-    Serial.println(central.address());
 
-    // Set the LED color to red when connected
-    nicla::leds.setColor(red);
+ // If a central device is connected
+ if (central) {
+   Serial.print("- Connected to central: ");
+   Serial.println(central.address());
 
-    // While the central device is connected
-    while (central.connected()) {
-      // Read the voltage level and update the BLE characteristic with the level value
-      int voltageLevel = readVoltageLevel();
 
-      Serial.print("- Voltage level is: ");
-      Serial.println(voltageLevel);
-      voltageLevelChar.writeValue(voltageLevel);
+   // Turn off the LED when disconnected
+   nicla::leds.setColor(blue);
 
-      delay(200);
-    }
-  }
 
-  // Turn off the LED when disconnected
-  nicla::leds.setColor(off);
+   // While the central device is connected
+   while (central.connected()) {
+     // Read the voltage level and update the BLE characteristic with the level value
+     int voltageLevel = readVoltageLevel();
+
+
+     Serial.print("- Voltage level is: ");
+     Serial.println(voltageLevel);
+     voltageLevelChar.writeValue(voltageLevel);
 
-  Serial.print("- Disconnected from central: ");
-  Serial.println(central.address());
+
+     delay(200);
+   }
+ }
+
+
+ // Turn off the LED when disconnected
+ nicla::leds.setColor(red);
+
+
+ Serial.print("- Disconnected from central: ");
+ Serial.println(central.address());
 }
 ```
 
-The example code shown above creates a Bluetooth® Low Energy service and characteristic for transmitting a voltage value read by one of the analog pins of the Nicla Voice to a central device. 
+The example code shown above creates a Bluetooth® Low Energy service and characteristic for transmitting a voltage value read by the analog pin A0 of the Nicla Voice to a central device Bluetooth® device like a smartphone or another microcontroller.
 
-- The code begins by importing all the necessary libraries and defining the Bluetooth® Low Energy service and characteristic.
+- The code begins by importing all the necessary libraries and defining the Bluetooth® Low Energy service and characteristics.
 - In the `setup()` function, the code initializes the Nicla Voice board and sets up the Bluetooth® Low Energy service and characteristic; then, it begins advertising the defined Bluetooth® Low Energy service.
-- A Bluetooth® Low Energy connection is constantly verified in the `loop()` function; when a central device connects to the Nicla Voice, its built-in LED is turned on (red). The code then enters into a loop that constantly reads the voltage level from an analog input and maps it to a percentage value between 0 and 100. The voltage level is printed to the Serial Monitor and transmitted to the central device over the defined Bluetooth® Low Energy characteristic.
+- A Bluetooth® Low Energy connection is constantly verified in the `loop()` function, being the built-in LED in red while looking for a connection. When a central device connects to the Nicla Voice, its built-in LED will change its color to blue. The code then enters into a loop that constantly reads the voltage level from an analog input and maps it to a percentage value between 0 and 100. The voltage level is printed to the Serial Monitor and transmitted to the central device over the defined Bluetooth® Low Energy characteristic.
+
+You can use the [nRF Connect for Mobile](https://www.nordicsemi.com/Products/Development-tools/nrf-connect-for-mobile) app from Nordic Semiconductor to test the functionality of the example code shown below. nRF Connect is a powerful tool that allows you to scan and explore Bluetooth® Low Energy devices and communicate with them.
+
+
+![Bluetooth® Low Energy service and characteristic information from a Nicla Voice device](assets/user-manual-bt.png)
+
 
 ### ESLOV Connector 
 
 The Nicla Voice board features an onboard ESLOV connector meant as an **extension** of the I2C communication bus. This connector simplifies connecting various sensors, actuators, and other modules to the Nicla Voice without soldering or wiring.
 
 ![Nicla Voice built-in ESLOV connector](assets/user-manual-8.png)
 
+
  The ESLOV connector is a small 5-pin connector with a 1.00 mm pitch; the mechanical details of the connector can be found in the connector's datasheet.
 
 The pin layout of the ESLOV connector is the following:
@@ -1473,4 +1481,4 @@ Join our community forum to connect with other Nicla Voice users, share your exp
 
 Please get in touch with our support team if you need personalized assistance or have questions not covered by the help and support resources described before. We're happy to help you with any issues or inquiries about the Nicla Voice.
 
-- [Contact us page](https://www.arduino.cc/en/contact-us/) 
+- [Contact us page](https://www.arduino.cc/en/contact-us/)