Beginner
10 min

Implement iButton™ technology into your projects with CZ-0-PIN and PIC32MZ2048EFH100

Secure and reliable data transfer with a simple touch

iButton Click with Flip&Click PIC32MZ

Published Mar 15, 2024

Click board™

iButton Click

Dev Board

Flip&Click PIC32MZ

Compiler

NECTO Studio

MCU

PIC32MZ2048EFH100

Create systems that require secure, physical touchpoints for data transfer or user identification

A

A

Hardware Overview

How does it work?

iButton Click is based on the CZ-0-PIN, a high-quality iButton probe from Demiurge. The metal probe ensures resistance to dirt, dust, moisture, shock, and other environmental hazards while ensuring good alignment with the iButton device. The manufacturer guarantees compatibility with Analog iButton devices, but the probe can read any other device compatible with the maxim iButton. The iButton device can power itself up through the data line by employing the so-called parasite power supply. This Click board™ is equipped with the pull-up resistor to the 3.3V mikroBUS™ rail, providing power for the iButton. The so-called parasite PSU of the iButton contains an internal capacitor, which

provides enough current for the proper operation once the data line has charged. To allow proper functioning of the parasitic PSU, the idle state of the data line is HIGH, while the data line of the iButton device is in an open-drain configuration, pulling the data line to a LOW logic level when asserted. The 1-Wire communication line is routed to the SMD jumper, which allows routing of the 1-Wire communication either to the PWM pin or to the AN pin of the mikroBUS™. These pins are labeled GP0 and GP1, respectively, the same as the SMD jumper positions, making the selection of the desired pin simple and straightforward. The green LED labeled as ST1 is routed to the RST pin of the

mikroBUS™, while the red LED is labeled as ST2 and is routed to the CS pin of the mikroBUS™. These two pins allow visual feedback from the software; for example, if the serial number of the docked iButton matches the authorization criteria, the green LED can signal it. These LEDs can be used for any signalization and are not directly connected to the iButton device. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used for further development.

iButton? Click hardware overview image

Features overview

Development board

Flip&Click PIC32MZ is a compact development board designed as a complete solution that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It comes with an onboard 32-bit PIC32MZ microcontroller, the PIC32MZ2048EFH100 from Microchip, four mikroBUS™ sockets for Click board™ connectivity, two USB connectors, LED indicators, buttons, debugger/programmer connectors, and two headers compatible with Arduino-UNO pinout. Thanks to innovative manufacturing technology,

it allows you to build gadgets with unique functionalities and features quickly. Each part of the Flip&Click PIC32MZ development kit contains the components necessary for the most efficient operation of the same board. In addition, there is the possibility of choosing the Flip&Click PIC32MZ programming method, using the chipKIT bootloader (Arduino-style development environment) or our USB HID bootloader using mikroC, mikroBasic, and mikroPascal for PIC32. This kit includes a clean and regulated power supply block through the USB Type-C (USB-C) connector. All communication

methods that mikroBUS™ itself supports are on this board, including the well-established mikroBUS™ socket, user-configurable buttons, and LED indicators. Flip&Click PIC32MZ development kit allows you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

Flip&Click PIC32MZ double image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC32

MCU Memory (KB)

2048

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

524288

You complete me!

Accessories

The DS1990A is a unique serial number identification iButton™. The iButton is a technology based on the one-wire communication protocol and a chip packed in a robust stainless steel casing. This button-shaped device has two contacts - the lid and the base. These contacts carry the necessary connections down to a sensitive silicone chip embedded inside the metal button. When the iButton touches the reader probe, it establishes the communication with the host MCU via the one-wire interface. The communication is almost instant, so pressing the iButton lightly to the probe contacts is enough.

iButton Click accessories 1 image

Used MCU Pins

mikroBUS™ mapper

1-Wire Data IN/OUT
RB11
AN
Status 2 Indicator
RE2
RST
Status 1 Indicator
RA0
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
1-Wire Data IN/OUT
RC14
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Schematic

iButton? Click Schematic schematic

Step by step

Project assembly

Flip&Click PIC32MZ front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Flip&Click PIC32MZ as your development board.

Flip&Click PIC32MZ front image hardware assembly
GNSS2 Click front image hardware assembly
Prog-cut hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
Flip&Click PIC32MZ MB1 Access - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Flip&Click PIC32MZ MCU step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for iButton Click driver.

Key functions:

  • ibutton_add_key - This function reads the ROM address from a DS1990A Serial Number iButton and stores it in the ctx->key_rom buffer

  • ibutton_remove_keys - This function removes all stored keys by clearing the ctx->key_rom buffer

  • ibutton_check_key - This function reads the ROM address from a DS1990A Serial Number iButton and checks if it is already stored in the ctx->key_rom buffer

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 main.c
 * @brief iButton Click Example.
 *
 * # Description
 * This example demonstrates the use of the iButton click boards by registering a DS1990A Serial Number iButton
 * key and then waiting until a key is detected on the reader and identifying if the key matches one of
 * those stored in RAM.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes the driver and registers a new DS1990A Serial Number iButton key and stores it in RAM.
 * 
 * ## Application Task  
 * Waits until a key is detected on the reader, and checks if there's a key found in the library that matches
 * the one it has just read. All data is being logged on the USB UART where you can track the program flow.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "ibutton.h"

#define NUMBER_OF_KEYS  1   // Number of keys to register.

static ibutton_t ibutton;
static log_t logger;

/**
 * @brief iButton led indication function.
 * @details This function indicates the selected state over LEDs indication.
 * @param[in] ctx : Click context object.
 * See #ibutton_t object definition for detailed explanation.
 * @param[in] state : @li @c 0 - Disable LEDs.
 *                    @li @c 1 - Wait for a key.
 *                    @li @c 2 - Operation successfull.
 *                    @li @c 3 - Wrong key found.
 * @return None.
 * @note None.
 */
static void ibutton_led_indication ( ibutton_t *ctx, ibutton_led_state_t state );

/**
 * @brief iButton register keys function.
 * @details This function registers a desired number of keys.
 * Each step will be logged on the USB UART where you can track the function flow.
 * @param[in] ctx : Click context object.
 * See #ibutton_t object definition for detailed explanation.
 * @param[in] num_keys : Number of keys to register.
 * @return None.
 * @note None.
 */
static void ibutton_register_keys ( ibutton_t *ctx, uint8_t num_keys );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    ibutton_cfg_t ibutton_cfg;  /**< Click config object. */

    /** 
     * 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.
    ibutton_cfg_setup( &ibutton_cfg );
    IBUTTON_MAP_MIKROBUS( ibutton_cfg, MIKROBUS_1 );
    if ( ONE_WIRE_ERROR == ibutton_init( &ibutton, &ibutton_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    ibutton_register_keys ( &ibutton, NUMBER_OF_KEYS );
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    err_t error_flag = IBUTTON_OK;
    ibutton_led_indication ( &ibutton, IBUTTON_LED_DISABLE );
    log_printf( &logger, " >>> Waiting for a key <<<\r\n" );
    do
    {
        ibutton_led_indication ( &ibutton, IBUTTON_LED_WAIT_KEY );
        error_flag = ibutton_check_key ( &ibutton );
    }
    while ( IBUTTON_ERROR == error_flag );

    ibutton_led_indication ( &ibutton, IBUTTON_LED_DISABLE );
    if ( IBUTTON_OK == error_flag )
    {
        log_printf( &logger, " MATCH, access allowed!\r\n" );
        ibutton_led_indication ( &ibutton, IBUTTON_LED_SUCCESS );
    }
    else if ( IBUTTON_KEY_NO_MATCH == error_flag )
    {
        log_printf( &logger, " NO MATCH, access denied!\r\n" );
        ibutton_led_indication ( &ibutton, IBUTTON_LED_WRONG_KEY );
    }
    ibutton_led_indication ( &ibutton, IBUTTON_LED_DISABLE );
    log_printf( &logger, "--------------------------------\r\n\n" );
    Delay_ms ( 500 );
}

int main ( void ) 
{
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

static void ibutton_led_indication ( ibutton_t *ctx, ibutton_led_state_t state )
{
    switch ( state )
    {
        case IBUTTON_LED_DISABLE:
        {
            ibutton_disable_green_led ( ctx );
            ibutton_disable_red_led ( ctx );
            break;
        }
        case IBUTTON_LED_WAIT_KEY:
        {
            ibutton_enable_green_led ( &ibutton );
            Delay_ms ( 250 );
            ibutton_disable_green_led ( &ibutton );
            ibutton_enable_red_led ( &ibutton );
            Delay_ms ( 250 );
            ibutton_disable_red_led ( &ibutton );
            break;
        }
        case IBUTTON_LED_SUCCESS:
        {
            ibutton_enable_green_led ( &ibutton );
            Delay_ms ( 250 );
            ibutton_disable_green_led ( &ibutton );
            Delay_ms ( 250 );
            ibutton_enable_green_led ( &ibutton );
            Delay_ms ( 250 );
            ibutton_disable_green_led ( &ibutton );
            Delay_ms ( 250 );
            break;
        }
        case IBUTTON_LED_WRONG_KEY:
        {
            ibutton_enable_red_led ( &ibutton );
            Delay_ms ( 250 );
            ibutton_disable_red_led ( &ibutton );
            Delay_ms ( 250 );
            ibutton_enable_red_led ( &ibutton );
            Delay_ms ( 250 );
            ibutton_disable_red_led ( &ibutton );
            Delay_ms ( 250 );
            break;
        }
        default:
        {
            break;
        }
    }
}

static void ibutton_register_keys ( ibutton_t *ctx, uint8_t num_keys )
{
    err_t error_flag = IBUTTON_OK;
    uint8_t key_cnt = 1;
    while ( key_cnt <= num_keys )
    {
        ibutton_led_indication ( &ibutton, IBUTTON_LED_DISABLE );
        log_printf( &logger, " >>> Registering key %u of %u <<<\r\n", ( uint16_t ) key_cnt, ( uint16_t ) num_keys );
        log_printf( &logger, " Insert a DS1990A Serial Number iButton to click board reader plate\r\n" );
        do
        {
            ibutton_led_indication ( &ibutton, IBUTTON_LED_WAIT_KEY );
            error_flag = ibutton_add_key ( &ibutton );
        }
        while ( IBUTTON_ERROR == error_flag );

        ibutton_led_indication ( &ibutton, IBUTTON_LED_DISABLE );
        if ( IBUTTON_KEY_ALREADY_EXIST == error_flag )
        {
            log_printf( &logger, " This key is already registered!\r\n" );
            log_printf( &logger, " Use another key or decrease the number of keys\r\n" );
            ibutton_led_indication ( &ibutton, IBUTTON_LED_WRONG_KEY );
        }
        else if ( IBUTTON_OK == error_flag )
        {
            log_printf( &logger, " The key is registered successfully!\r\n" );
            ibutton_led_indication ( &ibutton, IBUTTON_LED_SUCCESS );
            key_cnt++;
        }
        ibutton_led_indication ( &ibutton, IBUTTON_LED_DISABLE );
        log_printf( &logger, "--------------------------------\r\n\n" );
        Delay_ms ( 500 );
    }
}

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

Additional Support

Resources