Start Bit
/*Start first sensor*/
Sensor Address MSB (Bits 6-11)
Sensor Address LSB (Bits 0-5)
Sensor Instance
Sensor Data MSB (Bits 6-11)
Sensor Data LSB (Bits 0-5)
/*End first sensor*/
//Additional sensors/instances are included before the stop bit
Stop Bit

addr = (addrmsb << 6) | addrlsb; //Use this for true address value
data = (datamsb << 6) | datalsb; //Use this for true data value

0x80 //Start bit
0x00 //First SM-AFR Address MSB
0x00 //First SM-AFR Address LSB
0x00 //First SM-AFR Instance 1
0x00 //First SM-AFR Data MSB
0x04 //First SM-AFR Data LSB
0x00 //Second SM-AFR Address MSB
0x00 //Second SM-AFR Address LSB
0x01 //Second SM-AFR Instance 2 //value incremented
0x00 //Second SM-AFR Data MSB
0x05 //Second SM-AFR Data LSB
0x40 //Stop bit

Start bit ... Stop bit (waits indefinitely) (send a '+' then carriage return then '-' to obtain the next frame)

//C-pseudo code to reset device and read data
WriteTCP("atz\r"); //Resets device
WriteTCP("ate0\r"); //Turns echo off
Data = RequestPIDData(0x11, 1); //Request data from vehicle

if(PIDReadStatus == 2 | PIDReadStatus == 3) { //Check connection status
OBDConnected = 0;
} else { //Connected
OBDConnected = 1;
}

//Bluetooth communication will require write(byte[]) and read(byte[]) instead of WriteTCP() and ReadTCP()
int RequestPIDData(int PID,int bytes) //Pseudo C Code Example
{
int lsb,msb;
char c;
int b0,b1,b2,b3,b4,b5,b6,b7;
int Data;

lsb = (PID & 0x0f);
msb = ((PID & 0xf0)>>4);

WriteTCP('0');
WriteTCP('1');

if(msb == 0)
WriteTCP('0');
else if(msb == 1)
WriteTCP('1');
else if(msb == 2)
WriteTCP('2');
else if(msb == 3)
WriteTCP('3');
else if(msb == 4)
WriteTCP('4');
else if(msb == 5)
WriteTCP('5');
else if(msb == 6)
WriteTCP('6');
else if(msb == 7)
WriteTCP('7');
else if(msb == 8)
WriteTCP('8');
else if(msb == 9)
WriteTCP('9');
else if(msb == 10)
WriteTCP('A');
else if(msb == 11)
WriteTCP('B');
else if(msb == 12)
WriteTCP('C');
else if(msb == 13)
WriteTCP('D');
else if(msb == 14)
WriteTCP('E');
else if(msb == 15)
WriteTCP('F');

if(lsb == 0)
WriteTCP('0');
else if(lsb == 1)
WriteTCP('1');
else if(lsb == 2)
WriteTCP('2');
else if(lsb == 3)
WriteTCP('3');
else if(lsb == 4)
WriteTCP('4');
else if(lsb == 5)
WriteTCP('5');
else if(lsb == 6)
WriteTCP('6');
else if(lsb == 7)
WriteTCP('7');
else if(lsb == 8)
WriteTCP('8');
else if(lsb == 9)
WriteTCP('9');
else if(lsb == 10)
WriteTCP('A');
else if(lsb == 11)
WriteTCP('B');
else if(lsb == 12)
WriteTCP('C');
else if(lsb == 13)
WriteTCP('D');
else if(lsb == 14)
WriteTCP('E');
else if(lsb == 15)
WriteTCP('F');

WriteTCP(0x0d);

while(!DataRdyTCP());
c = ReadTCP();

if(c == 'N')
{
PIDReadStatus = 1; //No Data

//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
return 0;
}
else if(c == 'S')
{
PIDReadStatus = 2; //Searching

//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
return 0;
}
else if(c != '4')
{
PIDReadStatus = 3; //Anything else

//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
return 0;
}

while(!DataRdyTCP());
c = ReadTCP();
if(c != '1')
{
PIDReadStatus = 3; //Second character not 1

//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
return 0;
}

while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
c = ReadTCP(); //msb
while(!DataRdyTCP());
c = ReadTCP(); //lsb
while(!DataRdyTCP());
c = ReadTCP(); //space

if(bytes == 1) //data
{
while(!DataRdyTCP());
b0 = ReadTCP();
while(!DataRdyTCP());
b1 = ReadTCP();
b0 = CharToInt(b0);
b1 = CharToInt(b1);

Data = (b0<<4) + b1;

PIDReadStatus = 0;

//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
return Data;
}
else if(bytes == 2) //data
{
while(!DataRdyTCP());
b0 = ReadTCP();
while(!DataRdyTCP());
b1 = ReadTCP();
while(!DataRdyTCP());
c = ReadTCP();
while(!DataRdyTCP());
b2 = ReadTCP();
while(!DataRdyTCP());
b3 = ReadTCP();

b0 = CharToInt(b0);
b1 = CharToInt(b1);
b2 = CharToInt(b2);
b3 = CharToInt(b3);

Data = (b0<<12) + (b1<<8) + (b2<<4) + b3;

PIDReadStatus = 0;

//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
return Data;
}
else if(bytes == 4) //data
{
while(!DataRdyTCP());
b0 = ReadTCP();
while(!DataRdyTCP());
b1 = ReadTCP();
while(!DataRdyTCP());
c = ReadTCP();
while(!DataRdyTCP());
b2 = ReadTCP();
while(!DataRdyTCP());
b3 = ReadTCP();
while(!DataRdyTCP());
c = ReadTCP();
while(!DataRdyTCP());
b4 = ReadTCP();
while(!DataRdyTCP());
b5 = ReadTCP();
while(!DataRdyTCP());
c = ReadTCP();
while(!DataRdyTCP());
b6 = ReadTCP();
while(!DataRdyTCP());
b7 = ReadTCP();

b0 = CharToInt(b0);
b1 = CharToInt(b1);
b2 = CharToInt(b2);
b3 = CharToInt(b3);
b4 = CharToInt(b4);
b5 = CharToInt(b5);
b6 = CharToInt(b6);
b7 = CharToInt(b7);

Data = (b0<<28) + (b1<<24) + (b2<<20) + (b3<<16) + (b4<<12) + (b5<<8) + (b6<<4) + b7;

PIDReadStatus = 0;

//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
return Data;
}
}

int CharToInt(int c)
{
int i;

if(c == 48) //'0'
i = 0;
else if(c == 49) //'1'
i = 1;
else if(c== 50) //'2'
i = 2;
else if(c== 51) //'3'
i = 3;
else if(c== 52) //'4'
i = 4;
else if(c== 53) //'5'
i = 5;
else if(c== 54) //'6'
i = 6;
else if(c== 55) //'7'
i = 7;
else if(c== 56) //'8'
i = 8;
else if(c== 57) //'9'
i = 9;
else if(c== 65) //'A'
i = 10;
else if(c== 66) //'B'
i = 11;
else if(c== 67) //'C'
i = 12;
else if(c== 68) //'D'
i = 13;
else if(c== 69) //'E'
i = 14;
else if(c== 70) //'F'
i = 15;

return i;
}

//Pseudo C Code Example
int PIDConversion(int PID, int Data, int Units)
//Units parameter: 0 = Standard Units, 1 = Metric Units
{
double tempMPH;

if(PID == 0x11) //Throttle
return Data*100/255;
else if(PID == 0x0c) //RPM
return Data/4;
else if(PID == 0x0d) //Speed
{
if(Units == 0) // MPH
{
tempMPH = Data/1.609;
return(Round(tempMPH));
}
else
return Data; //KM/H
}
else if(PID == 0x04) //Engine Load
return Data*100/255;
else if(PID == 0x0E) //Timing Advance
{
if(Data < 128)
return (128 - Data)/2;
else
return (Data - 128)/2;
}
else if(PID == 0x0B) //Intake Manifold Pressure
{
if(Units == 0)
return Data/0.3386; //inHG
else
return Data; //Kpa
}
else if(PID == 0x10) //Air Flow Rate
{
if(Units == 0)
return Round(Data*0.013227736); //LBS/min
else
return Round(Data*0.01); //g/s
}
else if(PID == 0x03) //Fuel System Status
return (Data>>8) & 0xFF;
else if((PID == 0x06)|(PID == 0x07)|(PID == 0x08)|(PID == 0x09)) //Fuel TRIM
{
if(Data < 128)
return (128 - Data)*100/128;
else
return (Data - 128)*100/128;
}
else if((PID == 0x0F)|(PID == 0x05)) //AIT and Coolant
{
if(Units == 0) //Fahrenheit
{
if(Data < 40)
return 32;
else
return (Data-40)*9/5 + 32;
}
else //Celsius
{
if(Data < 40)
return 0;
else
return Data - 40;
}
}
else if(PID == 0x0A) //Fuel Pressure
{
if(Units == 0) //PSI
return Data*3*0.145;
else //KPA
return Data*3;
}
else if(PID == 0x1C) //OBD TYPE
return Data;
else if((PID == 0x14)|(PID == 0x15)|(PID == 0x18)|(PID == 0x19)) //O2 Voltage
return (Data >> 8)*0.5;
else if(PID == 0x2F) //Fuel Level Input
return Data*100/255;
else if(PID == 0x33) //Barometric Pressure
{
if(Units == 0)
return Data/0.3386; //inHG
else
return Data; //Kpa
}
else if((PID == 0x3C)|(PID == 0x3D)|(PID == 0x3E)|(PID == 0x3F)) //CAT Temperature
{
Data = Data*0.1;

if(Units == 0) //Fahrenheit
{
if(Data < 40)
return 32;
else
return (Data-40)*9/5 + 32;
}
else //Celsius
{
if(Data < 40)
return 0;
else
return Data - 40;
}
}
else if(PID == 0x42) //ECU Voltage
return Data*0.01;
else if(PID == 0x43) //ASB Engine Load
return Data*100/255;
else if(PID == 0x46) //Ambient Air Temperature
{
if(Units == 0) //Fahrenheit
{
if(Data < 40)
return 32;
else
return (Data-40)*9/5 + 32;
}
else //Celsius
{
if(Data < 40)
return 0;
else
return Data - 40;
}
}
else if(PID == 0x22) //FRP Rel
{
if(Units == 0)
return Data*0.79*0.145; //PSI
else
return Data*0.79; //Kpa
}
}

//Pseudo C Code Example
void ResetTroubleCode()
{
char c;

//Clear Input Buffer Here

//Reset Code
WriteTCP('0');
WriteTCP('4');
WriteTCP(0x0d);

//Wait for carriage return as precaution to system freeze.
while(!DataRdyTCP());
c = ReadTCP();
//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
}

//Pseudo C Code Example
void RequestNumberTrouble()
{
char c;

//Clear Input Buffer Here

WriteTCP('0');
WriteTCP('1');
WriteTCP('0');
WriteTCP('1');
WriteTCP(0x0d);

while(!DataRdyTCP());
c = ReadTCP();//4
while(!DataRdyTCP());
c = ReadTCP();//1
while(!DataRdyTCP());
c = ReadTCP();//space
while(!DataRdyTCP());
c = ReadTCP();//0
while(!DataRdyTCP());
c = ReadTCP();//1
while(!DataRdyTCP());
c = ReadTCP();//space
while(!DataRdyTCP());
c = ReadTCP();//0
while(!DataRdyTCP());
c = ReadTCP();//number of error codes

errornumber = c;

//The return string is long so wait for carriage return or else system will freeze.
while(!DataRdyTCP());
c = ReadTCP();
//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
}

//Pseudo C Code Example
void RequestTroubleCodes(int count) // Reads back 3 codes only.
{
int b0,b1,b2,b3; //Error 1
int b4,b5,b6,b7; //Error 2
int b8,b9,b10,b11; //Error 3
int c;
int x;

if(count == 0)
return;

//Clear Input Buffer Here

WriteTCP('0');
WriteTCP('3');
WriteTCP(0x0d);

//Non-CAN protocols
if(ConnectProtocol == 0)
{
while(!DataRdyTCP());
c = ReadTCP(); //4
while(!DataRdyTCP());
c = ReadTCP(); //3
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b0 = ReadTCP(); //Error1
while(!DataRdyTCP());
b1 = ReadTCP(); //Error1
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b2 = ReadTCP(); //Error1
while(!DataRdyTCP());
b3 = ReadTCP(); //Error1
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b4 = ReadTCP(); //Error2

while(!DataRdyTCP());
b5 = ReadTCP(); //Error2
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b6 = ReadTCP(); //Error2
while(!DataRdyTCP());
b7 = ReadTCP(); //Error2
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b8 = ReadTCP(); //Error3
while(!DataRdyTCP());
b9 = ReadTCP(); //Error3
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b10 = ReadTCP(); //Error3
while(!DataRdyTCP());
b11 = ReadTCP(); //Error3
}
else //CAN
{
if(count <= 2)
{
while(!DataRdyTCP());
c = ReadTCP(); //4
while(!DataRdyTCP());
c = ReadTCP(); //3
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
c = ReadTCP(); //Number Trouble
while(!DataRdyTCP());
c = ReadTCP(); //Number Trouble
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b0 = ReadTCP(); //Error1
while(!DataRdyTCP());
b1 = ReadTCP(); //Error1
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b2 = ReadTCP(); //Error1
while(!DataRdyTCP());
b3 = ReadTCP(); //Error1
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b4 = ReadTCP(); //Error2
while(!DataRdyTCP());
b5 = ReadTCP(); //Error2
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b6 = ReadTCP(); //Error2
while(!DataRdyTCP());
b7 = ReadTCP(); //Error2
}
else //3 or more trouble codes
{
while(!DataRdyTCP());
c = ReadTCP();
//Wait for ':'
while(c != ':')
{
while(!DataRdyTCP());
c = ReadTCP();
}

while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
c = ReadTCP(); //4
while(!DataRdyTCP());
c = ReadTCP(); //3
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
c = ReadTCP(); //Number Trouble
while(!DataRdyTCP());
c = ReadTCP(); //Number Trouble
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b0 = ReadTCP(); //Error1
while(!DataRdyTCP());
b1 = ReadTCP(); //Error1
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b2 = ReadTCP(); //Error1
while(!DataRdyTCP());
b3 = ReadTCP(); //Error1
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b4 = ReadTCP(); //Error2
while(!DataRdyTCP());
b5 = ReadTCP(); //Error2
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b6 = ReadTCP(); //Error2
while(!DataRdyTCP());
b7 = ReadTCP(); //Error2
while(!DataRdyTCP());
c = ReadTCP();
while(c != ':') //Wait for ':'
{
while(!DataRdyTCP());
c = ReadTCP();
}

while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b8 = ReadTCP(); //Error3
while(!DataRdyTCP());
b9 = ReadTCP(); //Error3
while(!DataRdyTCP());
c = ReadTCP(); //space
while(!DataRdyTCP());
b10 = ReadTCP(); //Error3
while(!DataRdyTCP());
b11 = ReadTCP(); //Error3
}
}

errb0 = b0;
errb1 = b1;
errb2 = b2;
errb3 = b3;
errb4 = b4;
errb5 = b5;
errb6 = b6;
errb7 = b7;
errb8 = b8;
errb9 = b9;
errb10 = b10;
errb11 = b11;

//For 4+ error codes - multiple lines are returned
while(!DataRdyTCP());
c = ReadTCP();
//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}
}

void ErrorCodePrefix(int b0)
{
if(b0 == 0)
{
hc = '0';
thc = 'P';
}
else if(b0 == 1)
{
hc = '1';
thc = 'P';
}
else if(b0 == 2)
{
hc = '2';
thc = 'P';
}
else if(b0 == 3)
{
hc = '3';
thc = 'P';
}
else if(b0 == 4)
{
hc = '0';
thc = 'C';
}
else if(b0 == 5)
{
hc = '1';
thc = 'C';
}
else if(b0 == 6)
{
hc = '2';
thc = 'C';
}
else if(b0 == 7)
{
hc = '3';
thc = 'C';
}
else if(b0 == 8)
{
hc = '0';
thc = 'b';
}
else if(b0 == 9)
{
hc = '1';
thc = 'b';
}
else if(b0 == 10)
{
hc = '2';
thc = 'b';
}
else if(b0 == 11)
{
hc = '3';
thc = 'b';
}
else if(b0 == 12)
{
hc = '0';
thc = 'U';
}
else if(b0 == 13)
{
hc = '1';
thc = 'U';
}
else if(b0 == 14)
{
hc = '2';
thc = 'U';
}
else if(b0 == 15)
{
hc = '3';
thc = 'U';
}
}

int GetProtocol() //returns 1 for CAN, 0 for other
{
char c;
char s[15];
int x;

//Clear Input Buffer Here

WriteTCP('a');
WriteTCP('t');
WriteTCP('d');
WriteTCP('p');
WriteTCP(0x0d);

getsTCP (s, 15); //Get a string of 15 characters

//The return string is long so wait for carriage return or else system will freeze.
while(!DataRdyTCP());
c = ReadTCP();
//Wait for OK>
while(c != 0x3E)
{
while(!DataRdyTCP());
c = ReadTCP();
}

for(x=0;x<11;x++)
{
if((s[x] == '1') & (s[x+1] == '5') & (s[x+2] == '7'))
return 1;
}
return 0;
}