OBD2 ELM327 Clone - Druckversion

Code:

#include <SoftwareSerial.h>



//Create an instance of the new soft serial library to control the serial LCD

//Note, digital pin 3 of the Arduino should be connected to Rx of the serial LCD.



SoftwareSerial lcd(2,3);



//This is a character buffer that will store the data from the serial port

char rxData[20];

char rxIndex=0;



//Variables to hold the speed and RPM data.

int vehicleSpeed=0;

int vehicleRPM=0;

Code:

void setup(){

  //Both the Serial LCD and the OBD-II-UART use 9600 bps.

  lcd.begin(9600);

  Serial.begin(9600);



  //Clear the old data from the LCD.

  lcd.write(254);

  lcd.write(1);  



  //Put the speed header on the first row.

  lcd.print("Speed: ");

  lcd.write(254);

  //Put the RPM header on the second row.

  lcd.write(128+64);

  lcd.print("RPM: ");



  //Wait for a little while before sending the reset command to the OBD-II-UART

  delay(1500);

  //Reset the OBD-II-UART

  Serial.println("ATZ");

  //Wait for a bit before starting to send commands after the reset.

  delay(2000);



  //Delete any data that may be in the serial port before we begin.

  Serial.flush();

}

Code:

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.

  lcd.write(254);

  lcd.write(128+8);

  //Clear out the old speed data, and reset the cursor position.

  lcd.print("        ");

  lcd.write(254);

  lcd.write(128+8);

  //Query the OBD-II-UART for the Vehicle Speed

  Serial.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 lcd

  lcd.print(vehicleSpeed);

  lcd.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.

  lcd.write(254);

  lcd.write(128 + 69);

  //Clear the old RPM data, and then move the cursor position back.

  lcd.print("          ");

  lcd.write(254);

  lcd.write(128+69);



  //Query the OBD-II-UART for the Vehicle rpm

  Serial.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 lcd

  lcd.print(vehicleRPM); 



  //Give the OBD bus a rest

  delay(100);



}

Code:

/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;

  //Keep reading characters until we get a carriage return

  while(inChar != '\r'){

    //If a character comes in on the serial port, we need to act on it.

    if(Serial.available() > 0){

      //Start by checking if we've received the end of message character ('\r').

      if(Serial.peek() == '\r'){

        //Clear the Serial buffer

        inChar=Serial.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 = Serial.read();

        //Add the new character to the string, and increment the index variable.

        rxData[rxIndex++]=inChar;

      }

    }

  }

}