problem with arduino connection to obdII to uart

Development Boards Arduino
1

Hello everyone ,

I’m using Arduino one and SparkFun Product

link SparkFun shield https://www.sparkfun.com/products/9555

I am following a tutorial on the SparkFun website and I have some doubts and problems that I can not solve.

my goal is ’ to connect the shield to the machine to perform a diagnostic service

I’m trying the code and ’ attached to the inside of the tutorial .

#include <SoftwareSerial.h>

//Create an instance of the new soft serial library to control the serial Serial
//Note, digital pin 3 of the Arduino should be connected to Rx of the serial Serial.


//This is a character buffer that will store the data from the serial port
char rxData[20];
char rxIndex=0;

SoftwareSerial OBD(5,6);
//Variables to hold the speed and RPM data.
int vehicleSpeed=0;
int vehicleRPM=0;

void setup(){
  //Both the Serial Serial and the OBD-II-UART use 9600 bps.
  Serial.begin(9600);
  OBD.begin(9600);
  //Clear the old data from the Serial.
   

  //Put the speed header on the first row.
  Serial.print("Speed: ");
  //Put the RPM header on the second row.
  
  Serial.print("RPM: ");

  //Wait for a little while before sending the reset command to the OBD-II-UART
  delay(1500);
  //Reset the OBD-II-UART
  OBD.println("ATZ");
  Serial.println("Risposta ELM327:");
 
   Serial.println(OBD.read());
  //Wait for a bit before starting to send commands after the reset.
  delay(10000);

  //Delete any data that may be in the serial port before we begin.
  Serial.flush();
}
void loop(){
  //Delete any data that may be in the serial port before we begin.  
  Serial.flush();
  //Set the cursor in the position where we want the speed data.
  
  //Clear out the old speed data, and reset the cursor position.
  Serial.print("        ");
  
  //Query the OBD-II-UART for the Vehicle Speed
  OBD.println("010D");
  //Get the response from the OBD-II-UART board. We get two responses
  //because the OBD-II-UART echoes the command that is sent.
  //We want the data in the second response.
  getResponse();
  getResponse();
  //Convert the string data to an integer
  vehicleSpeed = strtol(&rxData[6],0,16);
  //Print the speed data to the Serial
  Serial.print(vehicleSpeed);
  Serial.print(" km/h");
  delay(100);

  //Delete any data that may be left over in the serial port.
  Serial.flush();
  //Move the serial cursor to the position where we want the RPM data.
  
  //Clear the old RPM data, and then move the cursor position back.
  Serial.print("          ");
 

  //Query the OBD-II-UART for the Vehicle rpm
  OBD.println("010C");
  //Get the response from the OBD-II-UART board
  getResponse();
  getResponse();
  //Convert the string data to an integer
  //NOTE: RPM data is two bytes long, and delivered in 1/4 RPM from the OBD-II-UART
  vehicleRPM = ((strtol(&rxData[6],0,16)*256)+strtol(&rxData[9],0,16))/4;
  //Print the rpm data to the Serial
  Serial.print("Giri minuto=");
  Serial.print(vehicleRPM); 

  //Give the OBD bus a rest
  delay(1000);

}

//The getResponse function collects incoming data from the UART into the rxData buffer
// and only exits when a carriage return character is seen. Once the carriage return
// string is detected, the rxData buffer is null terminated (so we can treat it as a string)
// and the rxData index is reset to 0 so that the next string can be copied.
void getResponse(void){
  char inChar=0;
  Serial.println("sono nella getresponde");
  //Keep reading characters until we get a carriage return
  while(inChar != '\r'){
    Serial.println("leggo e aspetto il carattere di escape");
    Serial.println(inChar);
    //If a character comes in on the serial port, we need to act on it.
    if(OBD.available() > 0){
      Serial.println("arriva qualcosa");
      //Start by checking if we've received the end of message character ('\r').
      if(OBD.peek() == '\r'){
        //Clear the Serial buffer
        inChar=OBD.read();
        //Put the end of string character on our data string
        rxData[rxIndex]='\0';
        //Reset the buffer index so that the next character goes back at the beginning of the string.
        rxIndex=0;
      }
      //If we didn't get the end of message character, just add the new character to the string.
      else{
        //Get the new character from the Serial port.
        inChar = OBD.read();
        
        //Add the new character to the string, and increment the index variable.
        rxData[rxIndex++]=inChar;
      }
    }
  }
}

I slightly modified the code , the main differences are that I did not use an LCD to display data and I do not have the shield connected to the serial arduino but I did a serial communication on pins 5 and 6 through the library SoftwareSerial . Connecting Arduino to the machine I do not get the data sought but I get strange sequences of characters and the response to ’ at command " atz " is -1 or 255 if I change the baud rate . I tried " googling " the problem but have not found anything about it , I just thought that the problems may be due to the use of the software or the serial baud rate .

Have any of you ever encountered problems like this?

thank you all!