lately I have been working on a GPS reciever that supports both UBX and NEMA protocols. I am using serial programing on C++. I am trying to use UBX protocol, but it seems that I only recieve from NEMA. I downloaded the driver and I think I need to send a package first to recieve through UBX. Does anyone know a link or could tell me how could I send these packages the method I developed is stated below I think I need a small command before I start reading the data. Please someone help me here :D
void read_port(void)
{
unsigned char c='D';
while (c!='q')
{
if (read(fd, UBX_buffer, sizeof(UBX_buffer))>0)
{
data = read(fd, UBX_buffer, sizeof(UBX_buffer));
// write(fd,&UBX_buffer,1); // if new data is available on the serial port, print it out
cout<<"Data on the port = ";
for (unsigned i =0; i< sizeof(UBX_buffer) ;i++){
cout<<&UBX_buffer[i];
}
cout<<" "<<endl;
for (int i=0; i<fd; i++) // Process bytes received
{
switch(UBX_step) //we start from zero and increment as we go through the cases
{
case 0:
if(data==0xB5) UBX_step++; break; // UBX sync char 1 //check for the first data packet and go to next byte
case 1: if(data==0x62) UBX_step++;// UBX sync char 2 //check for the second data packet and go to the next byte
else UBX_step=0; break; //if first and second packets are not correct then go back and check again
case 2: UBX_class=data; checksum(UBX_class); UBX_step++; break;
case 3: UBX_id=data; checksum(UBX_id); UBX_step++; break;
case 4: UBX_payload_length_hi=data; checksum(UBX_payload_length_hi); UBX_step++; break;
case 5: UBX_payload_length_lo=data; checksum(UBX_payload_length_lo); UBX_step++; break;
case 6: // Payload data read...
if (UBX_payload_counter < UBX_payload_length_hi) // We stay in this state until we reach the payload_length
{
UBX_buffer[UBX_payload_counter] = data;
checksum(data);
UBX_payload_counter++;
}
else
UBX_step++;
break;
case 7: ck_a=data; UBX_step++; break; // First checksum byte
case 8: ck_b=data; // Second checksum byte
// We end the GPS read...
if((ck_a= ck_a)&&(ck_b= ck_a)) // Verify the received checksum with the generated checksum..
parse_ubx_gps(); // Parse new GPS packet...
UBX_step=0;
UBX_payload_counter=0;
ck_a=0;
ck_b=0;
GPS_timer=0; //Restarting timer...
break;
}
}
if (read(STDIN_FILENO,&c,1)>0) write(fd,&c,1); // if new data is available on the console, send it to the serial port
}
close(fd);
} // End Switch
} // End For