Intermediate
30 min

Design ultimate multiprotocol OBD solution with STN1110 and PIC32MZ1024EFH064

Revolutionize vehicle diagnostics

OBDII Click with PIC32MZ clicker

Published Aug 03, 2023

Click board™

OBDII Click

Dev. board

PIC32MZ clicker

Compiler

NECTO Studio

MCU

PIC32MZ1024EFH064

Innovative multiprotocol OBD-to-UART interface solution for seamless ECU communication, supporting multiple protocols and delivering vital data efficiently

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Hardware Overview

How does it work?

OBDII Click is based on the STN1110, a multiprotocol OBD to UART interface solution from ScanTool. This Click can be used for communication with the Electronic Control Unit (ECU) of a vehicle via several different OBD II diagnostic protocols such as CAN, K LINE, L LINE, and J1850. The STN1110 IC is used to process requests the MCU sends via the UART interface and return the responses from the ECU network nodes. The STN1110 multiprotocol OBD to UART IC is built around a fast 16-bit processor core with a large memory buffer. It also features automatic

protocol recognition, fully compatible with the ELM327 and ELM327 extended AT command set and can be used on UART speed up to 10Mbps. Those features make this click more than a perfect solution for various designs, including custom car dashboards, OBD data loggers, automotive diagnostic scan tools, and similar applications. To achieve successful communication with various systems used inside the vehicle diagnostic network, the STN1110 needs the signals to be converted on a physical level. For this reason, this board also comes equipped with the MCP2561 - an

ISO-11898 standard compliant CAN signal transceiver, as well as the LM339 - quad differential comparator IC, that is used to convert K Line, L Line, and J1850 line signals into a proper digital format. A separate analog pin is available on the STN1110 IC, which is used for the car battery voltage measurement. This function is handy when checking communication on the UART side of the IC. Besides requesting the voltage level information from the ECU via the command, it can also be measured directly from the battery voltage divider, with no special communication used.

OBDII Click hardware overview image

Features overview

Development board

PIC32MZ Clicker is a compact starter development board 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 with FPU from Microchip, a USB connector, LED indicators, buttons, a mikroProg connector, and a header for interfacing with external electronics. Thanks to its compact design with clear and easy-recognizable silkscreen markings, it provides a fluid and immersive working experience, allowing access anywhere and under

any circumstances. Each part of the PIC32MZ Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the PIC32MZ Clicker programming method, using USB HID mikroBootloader, or through an external mikroProg connector for PIC, dsPIC, or PIC32 programmer, the Clicker board also includes a clean and regulated power supply module for the development kit. The USB Micro-B connection can provide up to 500mA of current, which is more than enough to operate all onboard

and additional modules. All communication methods that mikroBUS™ itself supports are on this board, including the well-established mikroBUS™ socket, reset button, and several buttons and LED indicators. PIC32MZ Clicker is an integral part of the Mikroe ecosystem, allowing 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.

PIC32MZ clicker double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC32

MCU Memory (KB)

1024

Silicon Vendor

Microchip

Pin count

64

RAM (Bytes)

524288

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.

OBDII Click accessories image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Reset
RE5
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
Interrupt
RB5
INT
UART TX
RB2
TX
UART RX
RB0
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

OBDII Click Schematic schematic

Step by step

Project assembly

PIC32MZ clicker front image hardware assembly

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

PIC32MZ clicker front image hardware assembly
GNSS2 Click front image hardware assembly
Prog-cut hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
Micro B Connector Clicker 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

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 OBDII Click driver.

Key functions:

  • obdii_send_command - This function sends command string by using UART serial interface

  • obdii_generic_read - This function reads a desired number of data bytes by using UART serial interface

  • obdii_reset_device - This function resets the device by toggling the RST pin

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 OBDII Click Example.
 *
 * # Description
 * This example demonstrates the use of OBDII click board by reading the engine RPM
 * and vehicle speed and displaying results on the USB UART.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and performs the click default configuration.
 *
 * ## Application Task
 * Reads and processes the engine RPM and vehicle speed and displays the results
 * on the USB UART once per second.
 *
 * ## Additional Function
 * - static void obdii_clear_app_buf ( void )
 * - static err_t obdii_process ( obdii_t *ctx )
 * - static void obdii_log_app_buf ( void )
 * - static err_t obdii_rsp_check ( obdii_t *ctx, uint8_t *rsp )
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "obdii.h"
#include "conversions.h"

#define PROCESS_BUFFER_SIZE 200

static obdii_t obdii;
static log_t logger;

static uint8_t app_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
static int32_t app_buf_len = 0;

/**
 * @brief OBDII clearing application buffer.
 * @details This function clears memory of application buffer and reset its length.
 * @note None.
 */
static void obdii_clear_app_buf ( void );

/**
 * @brief OBDII data reading function.
 * @details This function reads data from device and concatenates data to application buffer. 
 * @param[in] ctx : Click context object.
 * See #obdii_t object definition for detailed explanation.
 * @return @li @c  0 - Read some data.
 *         @li @c -1 - Nothing is read.
 * See #err_t definition for detailed explanation.
 * @note None.
 */
static err_t obdii_process ( obdii_t *ctx );

/**
 * @brief Logs application buffer.
 * @details This function logs data from application buffer.
 */
static void obdii_log_app_buf ( void );

/**
 * @brief Response check.
 * @details This function checks for response and
 * returns the status of response.
 * @param[in] ctx : Click context object.
 * See #obdii_t object definition for detailed explanation.
 * @param[in] rsp  Expected response.
 * @return @li @c  0 - OK response.
 *         @li @c -1 - Unknown command.
 *         @li @c -2 - Timeout error.
 * See #err_t definition for detailed explanation.
 */
static err_t obdii_rsp_check ( obdii_t *ctx, uint8_t *rsp );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    obdii_cfg_t obdii_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.
    obdii_cfg_setup( &obdii_cfg );
    OBDII_MAP_MIKROBUS( obdii_cfg, MIKROBUS_1 );
    if ( UART_ERROR == obdii_init( &obdii, &obdii_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    obdii_reset_device ( &obdii );
    
    obdii_process ( &obdii );
    obdii_clear_app_buf ( );
    
    log_printf( &logger, "> Reset device\r\n" );
    obdii_send_command ( &obdii, OBDII_CMD_RESET_DEVICE );
    obdii_rsp_check ( &obdii, OBDII_RSP_PROMPT );
    obdii_log_app_buf ( );
    Delay_ms ( 1000 );
    
    log_printf( &logger, " Disable echo\r\n" );
    obdii_send_command ( &obdii, OBDII_CMD_DISABLE_ECHO );
    obdii_rsp_check ( &obdii, OBDII_RSP_PROMPT );
    obdii_log_app_buf ( );
    
    log_printf( &logger, " Remove spaces\r\n" );
    obdii_send_command ( &obdii, OBDII_CMD_SPACES_OFF );
    obdii_rsp_check ( &obdii, OBDII_RSP_PROMPT );
    obdii_log_app_buf ( );
}

void application_task ( void ) 
{
    uint8_t * __generic_ptr start_ptr = NULL;
    uint8_t data_buf[ 5 ] = { 0 };
    uint16_t rpm = 0;
    uint8_t speed = 0;
    
    log_printf( &logger, " Get current RPM\r\n" );
    obdii_send_command ( &obdii, OBDII_CMD_GET_CURRENT_RPM );
    obdii_rsp_check ( &obdii, OBDII_RSP_PROMPT );
    start_ptr = strstr( app_buf, OBDII_RSP_CURRENT_RPM );
    if ( start_ptr )
    {
        memcpy ( data_buf, ( start_ptr + 4 ), 4 );
        data_buf[ 4 ] = 0;
        rpm = hex_to_uint16( data_buf ) / 4;
        log_printf( &logger, "RPM: %u\r\n\n>", rpm );
    }
    else
    {
        obdii_log_app_buf ( );
    }
    
    log_printf( &logger, " Get current speed\r\n" );
    obdii_send_command ( &obdii, OBDII_CMD_GET_CURRENT_SPEED );
    obdii_rsp_check ( &obdii, OBDII_RSP_PROMPT );
    start_ptr = strstr( app_buf, OBDII_RSP_CURRENT_SPEED );
    if ( start_ptr )
    {
        memcpy ( data_buf, ( start_ptr + 4 ), 2 );
        data_buf[ 2 ] = 0;
        speed = hex_to_uint8( data_buf );
        log_printf( &logger, "Speed: %u km/h\r\n\n>", ( uint16_t ) speed );
    }
    else
    {
        obdii_log_app_buf ( );
    }
    Delay_ms ( 1000 );
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

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

static err_t obdii_process ( obdii_t *ctx ) 
{
    uint8_t rx_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
    int32_t rx_size = 0;
    rx_size = obdii_generic_read( ctx, rx_buf, PROCESS_BUFFER_SIZE );
    if ( rx_size > 0 ) 
    {
        int32_t buf_cnt = app_buf_len;
        if ( ( ( app_buf_len + rx_size ) > PROCESS_BUFFER_SIZE ) && ( app_buf_len > 0 ) ) 
        {
            buf_cnt = PROCESS_BUFFER_SIZE - ( ( app_buf_len + rx_size ) - PROCESS_BUFFER_SIZE );
            memmove ( app_buf, &app_buf[ PROCESS_BUFFER_SIZE - buf_cnt ], buf_cnt );
        }
        for ( int32_t rx_cnt = 0; rx_cnt < rx_size; rx_cnt++ ) 
        {
            if ( rx_buf[ rx_cnt ] ) 
            {
                app_buf[ buf_cnt++ ] = rx_buf[ rx_cnt ];
                if ( app_buf_len < PROCESS_BUFFER_SIZE )
                {
                    app_buf_len++;
                }
            }
        }
        return OBDII_OK;
    }
    return OBDII_ERROR;
}

static void obdii_log_app_buf ( void )
{
    for ( int32_t buf_cnt = 0; buf_cnt < app_buf_len; buf_cnt++ )
    {
        log_printf( &logger, "%c", app_buf[ buf_cnt ] );
    }
}

static err_t obdii_rsp_check ( obdii_t *ctx, uint8_t *rsp )
{
    uint32_t timeout_cnt = 0;
    uint32_t timeout = 60000;
    obdii_clear_app_buf( );
    obdii_process( ctx );
    while ( 0 == strstr( app_buf, rsp ) )
    {
        obdii_process( ctx );
        if ( timeout_cnt++ > timeout )
        {
            obdii_clear_app_buf( );
            return OBDII_ERROR_TIMEOUT;
        }
        Delay_ms ( 1 );
    }
    Delay_ms ( 100 );
    obdii_process( ctx );
    if ( strstr( app_buf, rsp ) )
    {
        return OBDII_OK;
    }
    return OBDII_ERROR;
}

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

Additional Support

Resources

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