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Enter the realm of secure CAN communication with ISO1042 and PIC18LF47K40

Drive your data forward with confidence!

CAN Isolator 2 Click with EasyPIC v7a

Published Nov 12, 2023

Click board™

CAN Isolator 2 Click

Development board

EasyPIC v7a

Compiler

NECTO Studio

MCU

PIC18LF47K40

This solution offers protection against ground potential differences, electrical noise, and voltage spikes, ensuring consistent and robust communication on the CAN bus.

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Hardware Overview

How does it work?

CAN Isolator 2 Click is based on the ISO1042, an isolated CAN transceiver from Texas Instruments. It has several features, such as undervoltage protection, driver Dominant Time Out (TXD DTO), HBM ESD tolerance on bus pins, and more. The transceiver has ideal passive high-impedance bus terminals when unpowered. If used in conjunction with the isolated power supplies, the CAN Isolator 2 Click can be the ideal choice for protection against high voltages and noise currents from the bus. There are two states of operation on this Click board™: dominant and recessive. In a dominant state, the bus is driven differentially by a driver. In a recessive state, the host MCU of the CAN node

uses the TXD pin to drive the bus and receives the data from the bus on the RXD pin. To connect ISO1042 on a CAN bus, this Click board™ features a standard DB 9-pin male connector. According to the ISO 11898-2 standard, a maximum bus length is 40m, and a maximum stub length is 0.3m, while with careful design, the cables could be longer. This transceiver has a high input impedance, thus allowing a large number of nodes on the CAN bus. CAN Isolator 2 Click uses a standard UART interface to communicate with the host MCU, with commonly used UART RX and TX. In addition, there are few headers to interface lines directly with jumper wires. The left side of the CAN Isolator

2 Click has a VEXT 2-pin header to connect the external power supply. Along with the VEXT, on the opposite side, there are CANH and CANL pins to interface the CAN bus in the same manner. Under the CAN header, there is also one TX and RX header, which allows this Click board™ to be used independently of the host MCU. 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 for further development.

CAN Isolator 2 Click hardware overview image

Features overview

Development board

EasyPIC v7a is the seventh generation of PIC development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as the first-ever embedded debugger/programmer over USB-C. 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 v7a allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of the EasyPIC v7a development board

contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board also includes a clean and regulated power supply module 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-C (USB-C) 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 v7a 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 v7a double side image

Microcontroller Overview

MCU Card / MCU

PIC18LF47K40

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

3728

You complete me!

Accessories

DB9 Cable Female-to-Female (2m) cable is essential for establishing dependable serial data connections between devices. With its DB9 female connectors on both ends, this cable enables a seamless link between various equipment, such as computers, routers, switches, and other serial devices. Measuring 2 meters in length, it offers flexibility in arranging your setup without compromising data transmission quality. Crafted with precision, this cable ensures consistent and reliable data exchange, making it suitable for industrial applications, office environments, and home setups. Whether configuring networking equipment, accessing console ports, or utilizing serial peripherals, this cable's durable construction and robust connectors guarantee a stable connection. Simplify your data communication needs with the 2m DB9 female-to-female cable, an efficient solution designed to meet your serial connectivity requirements easily and efficiently.

CAN Isolator 2 Click accessories 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
UART TX
RC6
TX
UART RX
RC7
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

CAN Isolator 2 Click Schematic schematic

Step by step

Project assembly

EasyPIC v7a front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v7a as your development board.

EasyPIC v7a front image hardware assembly
GNSS2 Click front image hardware assembly
MCU DIP 40 hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
EasyPIC v7a 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 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 CAN Isolator 2 Click driver.

Key functions:

  • canisolator2_generic_write - CAN Isolator 2 data writing function.

  • canisolator2_generic_read -CAN Isolator 2 data reading function.

  • canisolator2_send_data - CAN Isolator 2 send data 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 main.c
 * @brief CAN Isolator 2 Click Example.
 *
 * # Description
 * This example reads and processes data from CAN Isolator 2 clicks.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes driver and wake-up module.
 *
 * ## Application Task
 * Transmitter/Receiver task depends on uncommented code.
 * Receiver logging each received byte to the UART for data logging,
 * while transmitted send messages every 2 seconds.
 *
 * ## Additional Function
 * - static void canisolator2_clear_app_buf ( void )
 * - static err_t canisolator2_process ( void )
 *
 * @author Nenad Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "canisolator2.h"

#define PROCESS_BUFFER_SIZE 200

// #define TRANSMIT
#define RECIEVER

static canisolator2_t canisolator2;
static log_t logger;

static char app_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
static int32_t app_buf_len = 0;
static int32_t app_buf_cnt = 0;

unsigned char demo_message[ 9 ] = { 'M', 'i', 'k', 'r', 'o', 'E', 13, 10, 0 };

/**
 * @brief CAN Isolator 2 clearing application buffer.
 * @details This function clears memory of application buffer and reset it's length and counter.
 * @note None.
 */
static void canisolator2_clear_app_buf ( void );

/**
 * @brief CAN Isolator 2 data reading function.
 * @details This function reads data from device and concatenates data to application buffer.
 *
 * @return @li @c  0 - Read some data.
 *         @li @c -1 - Nothing is read.
 *         @li @c -2 - Application buffer overflow.
 *
 * See #err_t definition for detailed explanation.
 * @note None.
 */
static err_t canisolator2_process ( void );

void application_init ( void ) {
    log_cfg_t log_cfg;                    /**< Logger config object. */
    canisolator2_cfg_t canisolator2_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.

    canisolator2_cfg_setup( &canisolator2_cfg );
    CANISOLATOR2_MAP_MIKROBUS( canisolator2_cfg, MIKROBUS_1 );
    err_t init_flag  = canisolator2_init( &canisolator2, &canisolator2_cfg );
    if ( init_flag == UART_ERROR ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }

    app_buf_len = 0;
    app_buf_cnt = 0;
    log_info( &logger, " Application Task " );
    Delay_ms( 100 );
    
    #ifdef TRANSMIT
    
        log_printf( &logger, "    Send data:    \r\n" );
        log_printf( &logger, "      MikroE      \r\n" );
        log_printf( &logger, "------------------\r\n" );
        log_printf( &logger, "  Transmit data   \r\n" );
        Delay_ms( 1000 );

    #endif
        
    #ifdef RECIEVER

        log_printf( &logger, "   Receive data  \r\n" );
        Delay_ms( 2000 );
    
    #endif
        
    log_printf( &logger, "------------------\r\n" );
}

void application_task ( void ) {
   #ifdef TRANSMIT
    
        canisolator2_send_data( &canisolator2, demo_message );
        log_printf( &logger, "\t%s", demo_message );
        Delay_ms( 2000 );
        log_printf( &logger, "------------------\r\n" );    
    
    #endif
    
    #ifdef RECIEVER
    
        canisolator2_process( );

        if ( app_buf_len > 0 ) {
            log_printf( &logger, "%s", app_buf );
            canisolator2_clear_app_buf(  );
        }
    
    #endif
}

void main ( void ) {
    application_init( );

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

static void canisolator2_clear_app_buf ( void ) {
    memset( app_buf, 0, app_buf_len );
    app_buf_len = 0;
    app_buf_cnt = 0;
}

static err_t canisolator2_process ( void ) {
    int32_t rx_size;
    char rx_buff[ PROCESS_BUFFER_SIZE ] = { 0 };

    rx_size = canisolator2_generic_read( &canisolator2, rx_buff, PROCESS_BUFFER_SIZE );

    if ( rx_size > 0 ) {
        int32_t buf_cnt = 0;

        if ( app_buf_len + rx_size >= PROCESS_BUFFER_SIZE ) {
           canisolator2_clear_app_buf(  );
            return CANISOLATOR2_ERROR;
        } else {
            buf_cnt = app_buf_len;
            app_buf_len += rx_size;
        }

        for ( int32_t rx_cnt = 0; rx_cnt < rx_size; rx_cnt++ ) {
            if ( rx_buff[ rx_cnt ] != 0 ) {
                app_buf[ ( buf_cnt + rx_cnt ) ] = rx_buff[ rx_cnt ];
            } else {
                app_buf_len--;
                buf_cnt--;
            }

        }
        return CANISOLATOR2_OK;
    }
    return CANISOLATOR2_ERROR;
}

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

Additional Support

Resources