Intermediate
30 min
0

Create contactless access control systems with ST25DV16K and PIC18LF2553

NFC Extend: Your tags, your way, with endless antenna possibilities

NFC Extend Click with EasyPIC v7

Published Dec 29, 2023

Click board™

NFC Extend Click

Development board

EasyPIC v7

Compiler

NECTO Studio

MCU

PIC18LF2553

With NFC Extend, you have the power to shape your NFC experience with custom antennas, allowing you to personalize and adapt your tags to fit unique requirements

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Hardware Overview

How does it work?

NFC Extend Click is based on the ST25DV16K, a compact NFC tag IC from STMicroelectronics. The Click board™ itself has a reasonably small number of components because most of the interface and EEPROM memory circuitry is already integrated on the ST25DV16K IC. The I2C / SMBus compatible serial interface lines, along with the GPO pin, which also works in the open drain configuration, are pulled up by the on-board resistors. The 2-Wire lines are routed to the respective I2C lines of the mikroBUS™ (SCK and SDA), while the GPO pin of the main IC is routed to the INT pin of the mikroBUS™. Depending on the application requirements various shapes and sizes of 13.56 MHz external antenna can be used by connecting them to CN1 (male U.FL) connector. This Click can utilize new antennas that we have recently

released. The ST25DV16K uses the I2C/SMBus compatible communication interface, offering a fast transfer mode (FTM), to achieve a fast link between RF and contact worlds, via a 256 byte buffer called Mailbox. This mailbox dynamic buffer of 256 byte can be filled or emptied via either RF or I2C. There is also the INT pin available, which indicates incoming event to the contact side, like RF Field changes, RF activity in progress, RF writing completion or Mailbox message availability. The built in energy harvesting element can deliver µW of power when external conditions make it possible. The integrated RF management allows the NFC Extend Click to ignore RF requests. All these features can be programmed by setting static and/or dynamic registers of the ST25DV16K. The ST25DV16K can be partially customized

using configuration registers located in the E2 system area. More information about all the registers can be found in the ST25DV16K datasheet. However, provided library contains functions that simplify the use of the NFC Extend Click. The included application example demonstrates their functionality and it can be used as a reference for custom design. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

NFC Extend Click top side image
NFC Extend Click bottom side image

Features overview

Development board

EasyPIC v7 is the seventh generation of PIC development boards specially designed to develop embedded applications rapidly. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB-B. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyPIC v7 allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of

the EasyPIC v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use various external power sources, including an external 12V power supply, 7-23V AC or 9-32V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B) connector. Communication options such as

USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from PIC10F, PIC12F, PIC16F, PIC16Enh, PIC18F, PIC18FJ, and PIC18FK families. EasyPIC v7 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

EasyPIC v7 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

2048

You complete me!

Accessories

Circular NFC R35 Antenna is a circular-shaped PCB antenna designed to be used as an extension of development boards and placed remotely on desired places such as plastic casing, existing products, or even under displays. The antenna is designed in a circular shape with a diameter of 35mm (35x42mm WxL) and seven coil turns. It's also important to mention that this antenna can be used for NFC and RFID applications that work on 13.56MHz frequency.

NFC Extend Click accessories 1 image

UMCC - Ultraminiature Coax Connector is an ultra-low profile 1.37mm diameter coax female-to-female interconnect solution that meets the ever-growing demand for miniaturization in next-generation wireless applications. Crafted as double-ended jumpers and inter-series assemblies, the UMCC cable also offers PCB jack receptacles for seamless board mount applications. With a length (L) of 200mm, a 2.5mm mated height (H), and a 50 Ohm characteristic impedance, the UMCC Connector Type III ensures optimal performance across a broad frequency range from DC to 6 GHz.

NFC Extend Click accessories 2 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Interrupt
RB1
INT
NC
NC
TX
NC
NC
RX
I2C Clock
RC3
SCL
I2C Data
RC4
SDA
Power Supply
5V
5V
Ground
GND
GND
2

Take a closer look

Schematic

NFC Extend Click Schematic schematic

Step by step

Project assembly

EasyPIC v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v7 as your development board.

EasyPIC v7 front image hardware assembly
LTE IoT 5 Click front image hardware assembly
MCU DIP 28 hardware assembly
LTE IoT 5 Click complete accessories setup image hardware assembly
EasyPIC v7 Access MB 2 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto DIP image step 7 hardware assembly
EasyPIC PRO v7a Display Selection Necto Step hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

Library Description

This library contains API for NFC Extend Click driver.

Key functions:

  • nfcextend_i2c_set - This function writes data to the chip.

  • nfcextend_i2c_get - This function reads data from the chip.

  • nfcextend_digital_read_int - This function reads the digital signal from the INT pin.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

/*!
 * \file 
 * \brief NfcExtend Click example
 * 
 * # Description
 * This example showcases how to configure and use the NFC Extend click. The click is an NFC tag 
 * interface which uses the I2C serial interface and an RF link interface in order to communicate.
 * The example requires the ST25 NFC Tap application which can be downloaded to your phone.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * This function initializes and configures the logger and click modules.
 * 
 * ## Application Task  
 * This function waits for the interrupt signal, after which it expects data transfers. Once
 * some data has been detected it will open a communication channel with the device transmitting
 * it and show the received data in the UART console.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "nfcextend.h"

// ------------------------------------------------------------------ VARIABLES

static nfcextend_t nfcextend;
static log_t logger;

uint8_t default_password[ NFCEXTEND_PASSWORD_LEN ] = { 0 };

// ------------------------------------------------------- ADDITIONAL FUNCTIONS

void wait_for_interrupt ( )
{
    uint8_t int_pin_flag;
    uint16_t timer_counter;

    int_pin_flag = nfcextend_digital_read_int( &nfcextend );
    timer_counter = 0;
    
    while ( ( int_pin_flag == 1 ) && ( timer_counter <= 300 ) )
    {
        Delay_ms( 1 );
        timer_counter++;
        int_pin_flag = nfcextend_digital_read_int( &nfcextend );
    }

    if ( timer_counter <= 300 )
    {
        int_pin_flag = nfcextend_digital_read_int( &nfcextend );

        while ( int_pin_flag == 0 )
        {
            int_pin_flag = nfcextend_digital_read_int( &nfcextend );
        }
    }

    timer_counter = 0;
}

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( )
{
    log_cfg_t log_cfg;
    nfcextend_cfg_t cfg;

    uint8_t init_status_flag;

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, "---- Application Init ----" );

    //  Click initialization.

    nfcextend_cfg_setup( &cfg );
    NFCEXTEND_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    nfcextend_init( &nfcextend, &cfg );

    nfcextend_password_present( &nfcextend, default_password );
    Delay_ms( 100 );

    init_status_flag = nfcextend_default_cfg( &nfcextend );
    Delay_ms( 100 );

    if ( 1 == init_status_flag )
    {
        log_printf( &logger, " * App init failed. *\r\n" );
    }
    else if ( 0 == init_status_flag ) 
    {
        log_printf( &logger, " * App init done. *\r\n" );
    }
    log_printf( &logger, "-----------------------\r\n" );
}

void application_task ( )
{
    nfcextend_block_t block;

    uint8_t temp_buf[ 258 ];
    uint16_t message_len;
    uint16_t cnt;

    block.memory_area = NFCEXTEND_MEMORY_DYNAMIC;
    block.reg_addr = NFCEXTEND_DYNAMIC_REG_MB_CTRL;
    block.data_buf = temp_buf;
    block.len = 1;

    wait_for_interrupt( );
    nfcextend_i2c_get( &nfcextend, &block );

    if ( ( temp_buf[ 0 ] & 0x04 ) == 0x04 )
    {
        block.reg_addr = NFCEXTEND_DYNAMIC_REG_MB_LEN;
        block.data_buf = &temp_buf[ 0 ];

        wait_for_interrupt( );
        nfcextend_i2c_get( &nfcextend, &block );

        message_len = temp_buf[ 0 ] + 1;

        block.memory_area = NFCEXTEND_MEMORY_MAILBOX;
        block.reg_addr = NFCEXTEND_MAILBOX_REG_BYTE_0;
        block.data_buf = &temp_buf[ 0 ];
        block.len = message_len;

        wait_for_interrupt( );
        nfcextend_i2c_get( &nfcextend, &block );

        log_printf( &logger, " ** Message length:  %u Bytes**\r\n", message_len);
        
        log_printf( &logger, " ------------------------------\r\n" );
        log_printf( &logger, " ** Message START **\r\n" );

        for ( cnt = 0; cnt < message_len; cnt++ )
        {
            log_printf( &logger, " %u : 0x%x\r\n", cnt, ( uint16_t ) temp_buf[ cnt ] );
        }

        log_printf( &logger, " ** Message END **\r\n" );
        log_printf( &logger, " ------------------------------\r\n" );
    }
}

void main ( )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}

// ------------------------------------------------------------------------ END

Additional Support

Resources