Intermediate
30 min

Step into a new era of CXPI communication with BD41000AFJ-C and ATmega328P

Transcending communication limits

CXPI Click with Arduino UNO Rev3

Published Feb 14, 2024

Click board™

CXPI Click

Dev. board

Arduino UNO Rev3

Compiler

NECTO Studio

MCU

ATmega328P

Our advanced transceiver seamlessly integrates with CXPI networks, empowering efficient and reliable automotive communication for optimal data exchange in demanding environments

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Hardware Overview

How does it work?

CXPI Click is based on the BD41000AFJ-C, a transceiver for the Clock Extension Peripheral Interface (CXPI) communication from Rohm Semiconductor. The BD41000FJ-C complies with the CXPI standard established by JSAE (Society of Automotive Engineers of Japan), enabling highly responsive, reliable multiplex communication even in HMI systems, reducing vehicle weight and increasing fuel efficiency. The BD41000AFJ-C operates from 7V to 18V external power supply labeled as BAT and has several operating modes, each controlled by the CS pin of the mikroBUS™, BUS pin, and UART TX pin. It has built-in Power-OFF, Through, and RX Through other than CODEC Mode for power-saving control. Power-OFF Mode reduces power consumption by not supplying power to circuits other than necessary for Wake-Up pulse detection (BUS) and Wake-Up input

detection (TX). Through Mode does not process Coding/Decoding. It only directly drives signals from UART TX to BUS and from BUS to UART RX. RX Through Mode reverses RX output at each rising edge of BUS. CODEC Mode is the mode of CXPI communication. CS pin of the mikroBUS™ socket labeled as EN should be set high for the chip to enter CODEC Mode. The BD41000AFJ-C can achieve a quiescent 3uA (typ.) current, ensuring suitability with automotive applications. As a result, the battery load is minimized during non-operation, contributing to higher energy savings. Also, high ESD resistance (±8kV) makes achieving low-power, high-reliability CXPI communication possible. Besides, it has built-in fail-safe functions that suspend the output data upon detecting under-voltage or temperature abnormality. CXPI Click communicates

with MCU using the UART interface with a transmission speed range from 5kbps to 20kbps and commonly used UART RX and TX pins for data transfer. Also, it has three jumpers that allow the selection of CXPI transmitter mode on the MS pin of the BD41000AFJ-C to its appropriate position marked as Master or Slave. This can be performed by using the SMD jumpers labeled as MODE. Note that all the jumpers must be placed on the same side, or the Click board™ may become unresponsive. 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.

CXPI Click hardware overview image

Features overview

Development board

Arduino UNO is a versatile microcontroller board built around the ATmega328P chip. It offers extensive connectivity options for various projects, featuring 14 digital input/output pins, six of which are PWM-capable, along with six analog inputs. Its core components include a 16MHz ceramic resonator, a USB connection, a power jack, an

ICSP header, and a reset button, providing everything necessary to power and program the board. The Uno is ready to go, whether connected to a computer via USB or powered by an AC-to-DC adapter or battery. As the first USB Arduino board, it serves as the benchmark for the Arduino platform, with "Uno" symbolizing its status as the

first in a series. This name choice, meaning "one" in Italian, commemorates the launch of Arduino Software (IDE) 1.0. Initially introduced alongside version 1.0 of the Arduino Software (IDE), the Uno has since become the foundational model for subsequent Arduino releases, embodying the platform's evolution.

Arduino UNO Rev3 double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

AVR

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

2048

You complete me!

Accessories

Click Shield for Arduino UNO has two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the Arduino UNO board without effort. The Arduino Uno, a microcontroller board based on the ATmega328P, provides an affordable and flexible way for users to try out new concepts and build prototypes with the ATmega328P microcontroller from various combinations of performance, power consumption, and features. The Arduino Uno has 14 digital input/output pins (of which six can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header, and reset button. Most of the ATmega328P microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino UNO board with our Click Shield for Arduino UNO, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

Click Shield for Arduino UNO accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
Enable
PB2
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Master Mode: Clock Input
PD6
PWM
Slave Mode: Clock Output
PC3
INT
UART TX
PD0
TX
UART RX
PD1
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

CXPI Click Schematic schematic

Step by step

Project assembly

Click Shield for Arduino UNO front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino UNO Rev3 as your development board.

Click Shield for Arduino UNO front image hardware assembly
Arduino UNO Rev3 front image hardware assembly
Charger 27 Click front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Arduino UNO Rev3 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
Arduino UNO 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. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

Library Description

This library contains API for CXPI Click driver.

Key functions:

  • cxpi_send_command - Send command

  • cxpi_set_pwm_pin_state - Set PWM pin state function

  • cxpi_set_through_mode - Set through mode function.

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief CXPI Click Example.
 *
 * # Description
 * This is an example that demonstrates the use of the CXPI Click board.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes UART driver.
 * In addition to this module is placed inside transmitter/receiver working mode
 * cappable of transmission/receive the data.
 *
 * ## Application Task
 * Transmitter/Receiver task depend on uncommented code
 * Receiver logging each received byte to the UART for data logging,
 * while transmitted send messages every 5 seconds.
 *
 * ## Additional Function
 * - static void cxpi_clear_current_rsp_buf ( void )
 * - static void cxpi_process ( void )
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "cxpi.h"

#define PROCESS_COUNTER 10
#define PROCESS_RX_BUFFER_SIZE 100
#define PROCESS_PARSER_BUFFER_SIZE 100

//#define DEMO_APP_RECEIVER
#define DEMO_APP_TRANSMITTER

static cxpi_t cxpi;
static log_t logger;

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

/**
 * @brief CXPI clearing application buffer.
 * @details This function clears memory of application buffer and resets it's length and counter.
 */
static void cxpi_clear_current_rsp_buf ( void );

/**
 * @brief CXPI data reading function.
 * @details This function reads data from device and concatenates data to application buffer.
 */
static void cxpi_process ( void );

void application_init ( void ) {
    log_cfg_t log_cfg;  /**< Logger config object. */
    cxpi_cfg_t cxpi_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 );

    // Click initialization.

    cxpi_cfg_setup( &cxpi_cfg );
    CXPI_MAP_MIKROBUS( cxpi_cfg, MIKROBUS_1 );
    err_t init_flag  = cxpi_init( &cxpi, &cxpi_cfg );
    if ( UART_ERROR == init_flag ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }
    log_info( &logger, " Application Task " );
    cxpi_set_through_mode( &cxpi );

#ifdef DEMO_APP_TRANSMITTER
    log_printf( &logger, "------------------\r\n" );
    log_printf( &logger, "    Send data:    \r\n" );
    log_printf( &logger, "      MikroE      \r\n" );
    Delay_ms( 1000 );
#elif defined DEMO_APP_RECEIVER
    log_printf( &logger, "------------------\r\n" );
    log_printf( &logger, "   Receive data  \r\n" );
    Delay_ms( 2000 );
#else
    # error PLEASE SELECT TRANSMIT OR RECEIVE MODE!!!
#endif

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

void application_task ( void ) {
#ifdef DEMO_APP_TRANSMITTER
    cxpi_send_command( &cxpi, &demo_message[ 0 ] );
    log_printf( &logger, " Sent data : %s",  &demo_message[ 0 ] );
    log_printf( &logger, "------------------\r\n" ); 
    Delay_ms( 5000 );
#elif defined DEMO_APP_RECEIVER
    cxpi_process( );
    if ( current_rsp_buf > 0 ) {
        log_printf( &logger, "%s", current_rsp_buf );
        cxpi_clear_current_rsp_buf( );
    }
#else
    # error PLEASE SELECT TRANSMIT OR RECEIVE MODE!!!
#endif
}

void main ( void ) {
    application_init( );

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

static void cxpi_clear_current_rsp_buf ( void ) {
    memset( current_rsp_buf, 0, PROCESS_PARSER_BUFFER_SIZE );
}

static void cxpi_process ( void ) {
    int16_t rsp_size;
    uint16_t rsp_cnt = 0;

    char uart_rx_buffer[ PROCESS_RX_BUFFER_SIZE ] = { 0 };
    uint8_t check_buf_cnt;
    uint8_t process_cnt = PROCESS_COUNTER;

    // Clear parser buffer
    memset( current_rsp_buf, 0 , PROCESS_PARSER_BUFFER_SIZE ); 

    while( process_cnt != 0 ) {
        rsp_size = cxpi_generic_read( &cxpi, &uart_rx_buffer, PROCESS_RX_BUFFER_SIZE );

        if ( rsp_size > 0 ) {
            // Validation of the received data
            for ( check_buf_cnt = 0; check_buf_cnt < rsp_size; check_buf_cnt++ ) {
                if ( uart_rx_buffer[ check_buf_cnt ] == 0 ) {
                    uart_rx_buffer[ check_buf_cnt ] = 13;
                }
            }
            // Storages data in parser buffer
            rsp_cnt += rsp_size;
            if ( rsp_cnt < PROCESS_PARSER_BUFFER_SIZE ) {
                strncat( current_rsp_buf, uart_rx_buffer, rsp_size );
            }

            // Clear RX buffer
            memset( uart_rx_buffer, 0, PROCESS_RX_BUFFER_SIZE );
        } else {
            process_cnt--;
            // Process delay 
            Delay_ms( 100 );
        }
    }
}

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

Additional Support

Resources

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