Jc.OpenNov

Library for reading data from NFC Novo Nordisk insulin pens in .NET.

C# implementation derived from lcacheux's Kotlin nov-open-reader project - big thanks!

Table of Contents

• Introduction
• Usage
• Barebones (MAUI/etc.)
• Avalonia Android
• Avalonia iOS
• Avalonia

Introduction

Jc.OpenNov is a library designed to facilitate the reading of data from NFC Novo Nordisk insulin pens from iOS and Android in .NET.

Components

• Jc.OpenNov: Core library containing data structure and protocol implementation.
• Jc.OpenNov.Nfc.Android: Android implementation of NFC communication using Jc.OpenNov.
• Jc.OpenNov.Avalonia: Avalonia implementation of NFC communication using Jc.OpenNov.
• Jc.OpenNov.Avalonia.Android: Android implementation of NFC communication using Jc.OpenNov.Avalonia.
• Jc.OpenNov.Avalonia.iOS: iOS implementation of NFC communication using Jc.OpenNov.Avalonia.

Sample Screenshots

Android	iOS

Usage

Barebones (MAUI/etc.)

To use Jc.OpenNov, you need to install the NuGet package:

dotnet add package Jc.OpenNov

Followed by adding the Android/iOS Jc.OpenNov.Nfc.xxx package to your project:

dotnet add package Jc.OpenNov.Nfc.Android

Avalonia Android

Install the following NuGet packages to their respective projects:

dotnet add package Jc.OpenNov.Avalonia
dotnet add package Jc.OpenNov.Avalonia.Android

Add the following to your AndroidManifest.xml:

<uses-permission android:name="android.permission.NFC" />
<uses-feature android:name="android.hardware.nfc" android:required="true" />

In your MainActivity, add to your AppBuilder like so:

protected override AppBuilder CustomizeAppBuilder(AppBuilder builder)
{
    return base.CustomizeAppBuilder(builder)
        // ...
        .UseOpenNov(this);
}

Avalonia iOS

Install the following NuGet packages to their respective projects:

dotnet add package Jc.OpenNov.Avalonia
dotnet add package Jc.OpenNov.Avalonia.iOS

Add the following to your Entitlements.plist:

<key>com.apple.developer.nfc.readersession.formats</key>
<array>
    <string>TAG</string>
</array>

and the following to your Info.plist:

<key>NFCReaderUsageDescription</key>
<string>Used to retrieve data from Novopens.</string>
<key>com.apple.developer.nfc.readersession.iso7816.select-identifiers</key>
<array>
    <string>D2760000850101</string>
    <string>E103</string>
    <string>E104</string>
</array>

In your AppDelegate, add to your AppBuilder like so:

protected override AppBuilder CustomizeAppBuilder(AppBuilder builder)
{
    return base.CustomizeAppBuilder(builder)
        // ...
        .UseOpenNov();
}

Avalonia

To start listening for NFC tags, call:

OpenNov.Current.MonitorNfc(/* you may pass in an optional stop condition */);

Likewise, to stop listening for NFC tags, call:

OpenNov.Current.StopNfc();

To know when an NFC tag is detected and data is obtained, subscribe to the event handlers:

public MainViewModel()
{
    StarNfcCommand = ReactiveCommand.Create(StartNfc);
    StopNfcCommand = ReactiveCommand.Create(StopNfc);

    Avalonia.OpenNov.Current.OnDataRead += OnDataRead;
    Avalonia.OpenNov.Current.OnTagDetected += OnTagDetected;
    Avalonia.OpenNov.Current.OnError += OnError;
}

~MainViewModel()
{
    Avalonia.OpenNov.Current.OnDataRead -= OnDataRead;
    Avalonia.OpenNov.Current.OnTagDetected -= OnTagDetected;
    Avalonia.OpenNov.Current.OnError -= OnError;
}

private void OnDataRead(object? sender, Data.PenResult e)
{
    if (e is Data.PenResult.Success success)
    {
        Serial = success.Data.Serial;
    }
}

private void OnTagDetected(object? sender, ITag? e)
{
    var bytes = e?.GetId();
    if (bytes is null)
    {
        TagId = "Tag not found";
        return;
    }

    TagId = Convert.ToHexString(bytes);
}

private void OnError(object? sender, Exception e)
{
    Error = e.Message;
}