Learn how to build mobile apps to interact with NFC tags

Course Overview

What is NFC? An Introduction to NFC Tags, Cards, and Readers

Introduction

Tag Counter Game App

Set up a React Native NFC iOS and Android App

An Introduction to the React Native NFC Module Library

How to Build an iOS NFC Tag Scanner App With React Native

How to Build an Android NFC Tag Scanner App With React Native

App1 Conclusion

Tag-Counter Game App

Tap-And-Go App

How to Code an NDEF Message With the NFC Tools App

A Deep Dive Into NDEF and NdefRecord to Share Data via NFC

Tap-And-Go Project Setup With React Native and NFC Manager

How to Read NFC Tags and Write NDEF Data With NfcManager

How to Build a Website NFC Tag And Use Deep Linking With NFC

App2 Conclusion

Tap-And-Go  App

NFC Pokemon App

The User Flow of an NFC Tag Reader and Writer App

Intro to Type 2 NFC Tags: Read and Write NFC Tags With React

How to Sign and Verify NFC Data With React Native and elliptic

How to Add Memory Protection to NFC Tags For Copy Protection

App3 Conclusion

NfcPokemon  App

react

react-native

react-native-elements

react-native-nfc-manager

react-native-paper

## What we will cover in this course

First, I will provide an overview of NFC technology, so you can understand basic concepts and terms. After that, we will build three apps throughout this course.

### App 1: Tag Counter

![image](https://user-images.githubusercontent.com/10307875/148626752-38646752-bb16-4db2-8324-9fc19efdef04.png)

App 1 is a game app to count how much time a user needs to scan five NFC tags. You will learn:
- how to properly set up an NFC project 
- how to trigger NFC scanning
- the difference from iOS and Android regarding NFC feature

### App 2: Tap-and-Go

![image](https://user-images.githubusercontent.com/10307875/148627270-2dc43df8-8d5c-479d-8dd6-041b236d7009.png)

App 2 is about NFC Data Exchange Format (NDEF), which is the standard NFC data format supported by both iOS and Android. NDEF can be used for almost any NFC tag. We will build an NDEF reader-writer app, and you will learn:
- how to write specific NDEF URI into NFC tags 
- how to read NDEF URI and trigger corresponding actions, for example, opening an URL, making a phone call, or sending a message. 
- how to use deep linking with NFC tags.

### App 3: NFC Pokemon

![image](https://user-images.githubusercontent.com/10307875/148627203-562e742d-973e-406c-8e9e-a871ccdaf6d9.png)

App 3 dives into low-level NFC programming, which directly manipulates the NFC tag’s internal memory and uses proprietary NFC commands. 
The app we'll build is called "NFC Pokemon," which is a digital identity management platform. It can seal a specific Pokemon, for example, a Pikachu, into an NFC tag. 

When building this app, you will learn:
- how to use low-leve tag command to directly manipulate NFC tag's internal memory
- how to create digital signatures in React Native
- how to use proprietary password protection command for NXP NTAG 213 / 215

NFC technology is everywhere in our daily life, from transportation, access control, to payment system. However, understanding NFC is still a hard topic because of its wide technology landspace. 

So in this course, We will guide you from the simplest case like using common NDEF format, all the way to a complex digital identity management app which leverages some unique NFC features.

The newline Guide to NFCs with React Native

How to integrate NFC feature into your React Native app

How to handle the differences between Android and iOS regarding NFC feature

Understand NDEF and use it across iOS and Android

Understand low-level NFC programming and communicate with NFC tags directly

How to use asymmetric cryptography library with React Native

How to use password protection commands from NTAG 21x NFC tags

Hello, in this lesson, we will focus on how to read and write Pokemon data into NFC tags. 

As mentioned in the previous lesson, NFC-Forum classifies NFC tags into different Tag Platforms, from Type 2 to Type 5, and each of them has its own specification published as a standard.

Since we will focus on the Type 2 NFC tag (or T2T in short) in our course, let's take a look at the outline of this specification.

Among these chapters, I will walk you through:

This is the memory structure diagram for NFC Type 2 Tag.

The tag itself is divided into blocks containing four bytes each. The number associated with a block is also called "block number," which starts from 0.

The blocks can be further grouped into sectors. A sector is defined as 256 contiguous blocks. So one sector is 1024 bytes or 1Kilo Bytes.

However, most of the tags have a memory size less than 1KB, so they are always in sector 0.

The first three blocks contain two pieces of information. First is the UID, which is used as a unique hardware identifier. We will use it to calculate our digital signature in the following lessons. The second part is the lock bytes for memory protection purposes. These three blocks are normally programmed by the NFC tag manufacturer rather than us.

The next block, Capability Container, or CC block for short, is used to indicate whether the current tag complies with the NFC-Forum-defined tag platform specification and also contains some meta information for our NFC tags.

When a tag complies with Type 2 specification: 

Starting with block number 4, we have the DATA blocks, which are used to store application data. All Pokemon data in this course will be written into this area. 

The final "Lock & Reserved" blocks are often used by individual NFC Tag manufacturers to control their proprietary features, such as password protection, which will be discussed later in this course.

By the way, in the NFC domain, you might hear some people use the term "page" rather than "block." That's because some NFC manufacturers, like NXP, use this term in their proprietary documentation. But they mean the same thing: a 4-byte memory section in our NFC tag.

In this course, we might use these two terms, "block" and "page," interchangeably.

Next, let's talk about the commands for the NFC Type 2 Tag.

First is the READ command. This command has only two bytes. The first byte is the command code 0x30 in hex, and the second byte is the block number to start reading. The tag will respond by sending sixteen bytes, starting from the block number you passed. For example, if the block number passed is 4, then blocks 4, 5, 6, and 7 are returned. We can check if the response length is equal to 16 to know whether there are any errors.

Next is the WRITE command. This command is used to write one block into our NFC tags. The first byte is the command code A2 in hex, and the second byte is the block number, followed by 4 bytes of data you'd like to write.

---
title: "Intro to Type 2 NFC Tags: Read and Write NFC Tags With React"
isPublicLesson: false
privateVideoUrl: https://fullstack.wistia.com/medias/qoqkfr3ag3
---

Hello, in this lesson, we will focus on how to read and write Pokemon data into NFC tags. 

We will:

-   First learn to understand the NFC Type 2 Tag Platform, which includes:

    -   memory structure
    -   commands set
-   Implement our Pokemon read and write logic into our React Native app

Let's get started!

## Understand the Type 2 NFC tag

As mentioned in the previous lesson, NFC-Forum classifies NFC tags into different Tag Platforms, from Type 2 to Type 5, and each of them has its own specification published as a standard.

Since we will focus on the Type 2 NFC tag (or T2T in short) in our course, let's take a look at the outline of this specification.

Among these chapters, I will walk you through:

-   Chapter.2 Memory Structure and Management
-   Chapter.5 Command Set

## T2T memory structure

This is the memory structure diagram for NFC Type 2 Tag.

The tag itself is divided into blocks containing four bytes each. The number associated with a block is also called "block number," which starts from 0.

The blocks can be further grouped into sectors. A sector is defined as 256 contiguous blocks. So one sector is 1024 bytes or 1Kilo Bytes.

However, most of the tags have a memory size less than 1KB, so they are always in sector 0.

The first three blocks contain two pieces of information. First is the UID, which is used as a unique hardware identifier. We will use it to calculate our digital signature in the following lessons. The second part is the lock bytes for memory protection purposes. These three blocks are normally programmed by the NFC tag manufacturer rather than us.

The next block, Capability Container, or CC block for short, is used to indicate whether the current tag complies with the NFC-Forum-defined tag platform specification and also contains some meta information for our NFC tags.

When a tag complies with Type 2 specification: 

-   The first byte of this block should always be E1 in hex. This is a magic number defined by NFC-Forum.
-   The second byte encodes the spec version number it complies with. 
-   The third byte indicates the memory size of the data blocks divided by 8. For example, an NFC tag with 128 bytes data area should set this byte to 16 decimal, or 10 in hex
-   The last byte indicates the read and write access capability. The high nibble is for the read access, and the low nibble is for the write access. For both read and write, the value 0h indicates the operation granted without any security concern. All values other than 0 are either reserved or for proprietary usage defined by individual tag manufacturers. As you can see, this access control mechanism doesn't provide enough granularity for our application, so we choose to use a tag-specific password protection method for our application.

Starting with block number 4, we have the DATA blocks, which are used to store application data. All Pokemon data in this course will be written into this area. 

The final "Lock & Reserved" blocks are often used by individual NFC Tag manufacturers to control their proprietary features, such as password protection, which will be discussed later in this course.

By the way, in the NFC domain, you might hear some people use the term "page" rather than "block." That's because some NFC manufacturers, like NXP, use this term in their proprietary documentation. But they mean the same thing: a 4-byte memory section in our NFC tag.

In this course, we might use these two terms, "block" and "page," interchangeably.

## T2T commands

Next, let's talk about the commands for the NFC Type 2 Tag.

First is the READ command. This command has only two bytes. The first byte is the command code 0x30 in hex, and the second byte is the block number to start reading. The tag will respond by sending sixteen bytes, starting from the block number you passed. For example, if the block number passed is 4, then blocks 4, 5, 6, and 7 are returned. We can check if the response length is equal to 16 to know whether there are any errors.

Next is the WRITE command. This command is used to write one block into our NFC tags. The first byte is the command code A2 in hex, and the second byte is the block number, followed by 4 bytes of data you'd like to write.

When the write operation is successful, it will return a single byte response: A in hex, or 10 in decimal. Otherwise, we can treat it as an error.

In our NFC library, we can use `NfcManager.nfcAHandler.transceive` to send the above commands, as we will see in the coding section.

## Recap Pokemon review process

Before jumping into writePokemon function, let's review the full Pokemon tag creation process again. 

We have seen this code structure several times: the whole onPress handler has been wrapped into a try-catch-finally block. In the try block, we issue a `NfcManager.requestTechnology` API; the desired NFC technology is NfcA. The finally block issues a `cancelTechnology` API to stop the NFC scanning process. 

Intro to Type 2 NFC Tags: Read and Write NFC Tags With React

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