Hello, I really need your help.
I tried to use the "LED" example from the ArduinoBLE library.
I upload the code into the NICLA SENSE ME and try to reach it through the smarthphone with LightBlue app.
I found the device and the new Characteristic but when I try to write a value I get a message says "Failed to write to characteristic properly. Status: 7"
Why does it happening? what did I do wrong?
thanks for helping 
Here is my code: (I used the example but remove the pins commands cause I didnt connected anything to the NICLA)\
LED
This example creates a Bluetooth® Low Energy peripheral with service that contains a
characteristic to control an LED.
The circuit:
- Arduino MKR WiFi 1010, Arduino Uno WiFi Rev2 board, Arduino Nano 33 IoT,
Arduino Nano 33 BLE, or Arduino Nano 33 BLE Sense board.
You can use a generic Bluetooth® Low Energy central app, like LightBlue (iOS and Android) or
nRF Connect (Android), to interact with the services and characteristics
created in this sketch.
This example code is in the public domain.
*/
#include <ArduinoBLE.h>
BLEService ledService("19B10000-E8F2-537E-4F6C-D104768A1214"); // Bluetooth® Low Energy LED Service
// Bluetooth® Low Energy LED Switch Characteristic - custom 128-bit UUID, read and writable by central
BLEByteCharacteristic switchCharacteristic("19B10001-E8F2-537E-4F6C-D104768A1214", BLERead | BLEWrite);
const int ledPin = LED_BUILTIN; // pin to use for the LED
void setup() {
Serial.begin(9600);
while (!Serial);
// set LED pin to output mode
pinMode(ledPin, OUTPUT);
// begin initialization
if (!BLE.begin()) {
Serial.println("starting Bluetooth® Low Energy module failed!");
while (1);
}
// set advertised local name and service UUID:
BLE.setLocalName("LED");
BLE.setAdvertisedService(ledService);
// add the characteristic to the service
ledService.addCharacteristic(switchCharacteristic);
// add service
BLE.addService(ledService);
// set the initial value for the characeristic:
switchCharacteristic.writeValue(0);
// start advertising
BLE.advertise();
Serial.println("BLE LED Peripheral");
}
void loop() {
// listen for Bluetooth® Low Energy peripherals to connect:
BLEDevice central = BLE.central();
// if a central is connected to peripheral:
if (central) {
Serial.print("Connected to central: ");
// print the central's MAC address:
Serial.println(central.address());
// while the central is still connected to peripheral:
while (central.connected()) {
// if the remote device wrote to the characteristic,
// use the value to control the LED:
if (switchCharacteristic.written()) {
if (switchCharacteristic.value()) { // any value other than 0
Serial.println("LED on");
digitalWrite(ledPin, HIGH); // will turn the LED on
} else { // a 0 value
Serial.println(F("LED off"));
digitalWrite(ledPin, LOW); // will turn the LED off
}
}
}
// when the central disconnects, print it out:
Serial.print(F("Disconnected from central: "));
Serial.println(central.address());
}
}