The device addressing sequence stars with the most significant bit (MSB) first and ends with the least significant bit (LSB) and it’s actually composed of 7 bits because the 8 th bit is used for indicating whether the master will write to the slave (logic low) or read from it (logic high).

After this the clock starts and each data bit is transferred during each clock pulse. The start condition occurs when data line drops low while the clock line is still high. Let’s take even closer look at these events. Right after the addressing sequences follows the data sequences as many until the data is completely sent and it ends with a special stop condition. After the first Acknowledge bit in most cases comes another addressing sequence but this time for the internal registers of the slave device. After each 8 bits sequence follows a bit called Acknowledge. So after a special start condition occurs comes the first 8 bits sequence which indicates the address of the slave to which the data is being sent.

Create a quick-start node that reads an NFC tag to serve most common purposes.The data signal is transferred in sequences of 8 bits.

For the new type, create action nodes that correspond to the functions and methods provided by the third-party C++ library.

Declare a dependency on a third-party C++ library so that XOD knows where to download it, saving users from manual install.

There may be several instances of this node, one for each hardware module.

Declare a new custom type pn532-device, which describes an RFIC/NFC module and how is it connected to an Arduino board.

In order not to go into the details of working with tags, we will take the Adafruit-PN532 Arduino library and just wrap it in XOD nodes. Imagine that we want our Arduino board to turn the built-in led on or off when we bring an NFC tag, such as travel pass, to it.Ĭonsider that we have no XOD library to work with RFID/NFC scanner PN532 ( xod-dev/pn532-nfc), and try to make it on our own. Also, you need to have some experience of working with C++ libraries for Arduino. To understand this guide, you have to know how to write C++ code in XOD and how to work with custom types. Many libraries already have been written for Arduino and they can be included into XOD to use the full power of the existing ecosystem.

Download arduino wire library