Intermediate
30 min
0

Step into a new era of CXPI communication with BD41000AFJ-C and STM32L162ZE

Transcending communication limits

CXPI Click with Fusion for STM32 v8

Published Aug 13, 2023

Click board™

CXPI Click

Development board

Fusion for STM32 v8

Compiler

NECTO Studio

MCU

STM32L162ZE

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

Fusion for STM32 v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different 32-bit ARM® Cortex®-M based MCUs from STMicroelectronics, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, Fusion for STM32 v8 provides a fluid and immersive working experience, allowing

access anywhere and under any circumstances at any time. Each part of the Fusion for STM32 v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.

Communication options such as USB-UART, USB HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. Fusion for STM32 v8 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.

Fusion for STM32 v8 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Type

8th Generation

Architecture

ARM Cortex-M3

MCU Memory (KB)

512

Silicon Vendor

STMicroelectronics

Pin count

144

RAM (Bytes)

81920

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
Enable
PD11
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Master Mode: Clock Input
PD12
PWM
Slave Mode: Clock Output
PG6
INT
UART TX
PB6
TX
UART RX
PB7
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

CXPI Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Fusion for STM32 v8 as your development board.

Fusion for PIC v8 front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
v8 SiBRAIN 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 image step 7 hardware assembly
Necto image step 8 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 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

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 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