Beginner
10 min

Ensure secure I2C data exchange with ISO1540 and PIC18F57Q43

Completely isolated, completely bidirectional I2C

I2C Isolator Click with Curiosity Nano with PIC18F57Q43

Published Feb 13, 2024

Click board™

I2C Isolator Click

Dev Board

Curiosity Nano with PIC18F57Q43

Compiler

NECTO Studio

MCU

PIC18F57Q43

Take your engineering solution to the next level with isolated bidirectional I2C-compatible communication

A

A

Hardware Overview

How does it work?

I2C Isolator Click is based on the ISO1540, a 2.5kVrms I2C digital isolator from Texas Instruments. The ISO1540 enables a completely isolated I2C interface, supporting Fast Mode Plus up to 1MHz, with two isolated bidirectional channels for clock and data lines. It provides advantages such as performance, size, and power consumption compared to optocouplers, which makes it suitable for multi-master and applications where slave clock stretching is possible. Isolated bidirectional communication is accomplished by offsetting the low-level output

voltage on the MCU side to a value greater than its high-level input voltage, preventing an internal logic latch that would occur with standard digital isolators. The ISO1540 has logic input and output buffers separated by Texas Instruments Capacitive Isolation technology using a silicon dioxide (SiO2) barrier. Also, the ISO1540 internally splits a bidirectional line into two unidirectional lines, each isolated through a single-channel digital isolator. This way, each channel output is made open-drain to comply with the open-drain technology of I2C. When used with isolated

power supplies, the ISO1540 blocks high voltages, isolates grounds, and prevents noise currents from entering the local ground and interfering with or damaging sensitive circuitry. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC1 SEL jumper. Therefore, both 3.3V and 5V capable MCUs to use the communication lines properly. The 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.

I2C Isolator Click hardware overview image

Features overview

Development board

PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive

mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI

GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.

PIC18F57Q43 Curiosity Nano double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

48

RAM (Bytes)

8196

You complete me!

Accessories

Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.

Curiosity Nano Base for Click boards accessories 1 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
NC
NC
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PB1
SCL
I2C Data
PB2
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

I2C Isolator Click Schematic schematic

Step by step

Project assembly

Curiosity Nano Base for Click boards front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.

Curiosity Nano Base for Click boards front image hardware assembly
Charger 27 Click front image hardware assembly
PIC18F47Q10 Curiosity Nano front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Curiosity Nano with PICXXX Access MB 1 - 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
PIC18F57Q43 Curiosity 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

1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.

2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.

DEBUG_Application_Output

Software Support

Library Description

This library contains API for I2C Isolator Click driver.

Key functions:

  • i2cisolator_generic_write - Generic write function

  • i2cisolator_generic_read - Generic read function

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 I2Cisolator Click example
 * 
 * # Description
 * This is an example which demonstrates the use of I2C Isolator Click board.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initialization driver enables - I2C,
 * sets configuration of TMP007 sensor on IrThermo 2 click and start to write log.
 * 
 * ## Application Task  
 * In this example we use IrThermo 2 click, measures the temperature with,
 * and calculate the temperature in degrees Celsius [ C ].
 * Results are being sent to the USART Terminal where you can track their changes.
 * All data logs on usb uart each second.
 * 
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "i2cisolator.h"

/* Register Address */
#define I2CISOLATOR_IRTHERMO2_CONFIGURATION                       0x02
#define I2CISOLATOR_IRTHERMO2_OBJECT_TEMPERATURE              0x03
#define I2CISOLATOR_IRTHERMO2_STATUS_MASK_AND_ENABLE       0x05

/* Commands */       
#define I2CISOLATOR_IRTHERMO2_CFG_MODEON                           0x1000
#define I2CISOLATOR_IRTHERMO2_CFG_ALERTEN                           0x0100
#define I2CISOLATOR_IRTHERMO2_CFG_TRANSC                            0x0040
#define I2CISOLATOR_IRTHERMO2_CFG_16SAMPLE                         0x0800
#define I2CISOLATOR_IRTHERMO2_STAT_ALERTEN                         0x8000
#define I2CISOLATOR_IRTHERMO2_STAT_CRTEN                            0x4000

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

static i2cisolator_t i2cisolator;
static log_t logger;
static float temperature;

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

void i2cisolator_get_temperature ( void )
{
    uint8_t temp_data[ 2 ];
    uint16_t temp;
    
    i2cisolator_generic_read( &i2cisolator, I2CISOLATOR_IRTHERMO2_OBJECT_TEMPERATURE, temp_data, 2 );
    
    temp = temp_data[ 0 ];
    temp <<= 8;
    temp |= temp_data[ 1 ];
    temp >>= 2;
    temperature = ( float ) temp;
    temperature *= 0.03125;
}

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    i2cisolator_cfg_t cfg;
    uint8_t tmp;

    /** 
     * 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.

    i2cisolator_cfg_setup( &cfg );
    I2CISOLATOR_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    i2cisolator_init( &i2cisolator, &cfg );

    log_printf( &logger, "    Driver  Initialized\r\n" );
    log_printf( &logger, "---------------------------\r\n" );
    Delay_ms( 100 );
    
    tmp =    I2CISOLATOR_IRTHERMO2_CFG_MODEON |
                I2CISOLATOR_IRTHERMO2_CFG_ALERTEN | 
                I2CISOLATOR_IRTHERMO2_CFG_TRANSC | 
                I2CISOLATOR_IRTHERMO2_CFG_16SAMPLE;
    i2cisolator_generic_write( &i2cisolator, I2CISOLATOR_IRTHERMO2_CONFIGURATION, &tmp, 1 );

    tmp =    I2CISOLATOR_IRTHERMO2_STAT_ALERTEN | 
                I2CISOLATOR_IRTHERMO2_STAT_CRTEN;
    i2cisolator_generic_write( &i2cisolator, I2CISOLATOR_IRTHERMO2_STATUS_MASK_AND_ENABLE, &tmp, 1 );    
    
    log_printf( &logger, "       Configuration\r\n" );
    log_printf( &logger, "      IrThermo 2 Click\r\n" );
    log_printf( &logger, "---------------------------\r\n" );
    Delay_ms( 100 );
}

void application_task ( void )
{
    i2cisolator_get_temperature( );   
    
    log_printf( &logger, " Temperature : %0.2f C\r\n", temperature );
    log_printf( &logger, "---------------------------\r\n" );
    Delay_ms( 1000 );
}

void main ( void )
{
    application_init( );

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


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

Additional Support

Resources

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