Binary data from a serial port in linux using c
- by user1680393
I am reading binary data from a serial port on Phidget sbc using Linux to get a command from an application running on a PC. I wrote a test program in VB to read the data into a byte array and convert it to decimal to use it but can’t figure out how to do it in c. I am unable to come up with anything with the research I have done on the internet.
Command sent from PC is 0x0F.
To check if I am getting correct data I read the data and send it back. Here is what I get back. Returned data has a carriage return added to it.
Hex Display 0F00 0000 0D
‘\’ Display \0F\00\00\00\r
Normal display just display a strange character.
This tells me that the data is there that I can use, but can’t figure out to extract the value 0F or 15.
How can I convert the incoming data to use it?
I tried converting the received data using strtol, but it returns 0. I also tried setting the port to raw but it did not make any difference.
unsigned char buffer1[1];
int ReadPort1()
{
int result;
result = read(file1, &buffer1,1);
if(result > 0)
{
WritePort1(buffer1);
sprintf(tempstr, "Port1 data %s %d", buffer1, result);
DisplayText(2,tempstr);
}
return result;
}
Port Open/Setup
void OpenPort1()
{
//file1 = open("/dev/ttyUSB1", O_RDWR | O_NOCTTY | O_NONBLOCK);
file1 = open("/dev/ttyUSB1", O_RDWR | O_NOCTTY | O_NODELAY);
if(file1 < 0)
printf("Error opening serial port1.\n");
else
{
SetPort(file1, 115200, 8, 1, 0, 1);
port1open = 1;
}
}
void SetPort(int fd, int Baud_Rate, int Data_Bits, int Stop_Bits, int Parity, int raw)
{
long BAUD; // derived baud rate from command line
long DATABITS;
long STOPBITS;
long PARITYON;
long PARITY;
struct termios newtio;
switch (Baud_Rate)
{
case 115200:
BAUD = B115200;
break;
case 38400:
BAUD = B38400;
break;
case 19200:
BAUD = B19200;
break;
case 9600:
BAUD = B9600;
break;
} //end of switch baud_rate
switch (Data_Bits)
{
case 8:
default:
DATABITS = CS8;
break;
case 7:
DATABITS = CS7;
break;
case 6:
DATABITS = CS6;
break;
case 5:
DATABITS = CS5;
break;
} //end of switch data_bits
switch (Stop_Bits)
{
case 1:
default:
STOPBITS = 0;
break;
case 2:
STOPBITS = CSTOPB;
break;
} //end of switch stop bits
switch (Parity)
{
case 0:
default: //none
PARITYON = 0;
PARITY = 0;
break;
case 1: //odd
PARITYON = PARENB;
PARITY = PARODD;
break;
case 2: //even
PARITYON = PARENB;
PARITY = 0;
break;
} //end of switch parity
newtio.c_cflag = BAUD | DATABITS | STOPBITS | PARITYON | PARITY | CLOCAL | CREAD;
newtio.c_iflag = IGNPAR;
if(raw == 1)
{
newtio.c_oflag &= ~OPOST;
newtio.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
}
else
{
newtio.c_lflag = 0; //ICANON;
newtio.c_oflag = 0;
}
newtio.c_cc[VMIN]=1;
newtio.c_cc[VTIME]=0;
tcflush(fd, TCIFLUSH);
tcsetattr(fd,TCSANOW,&newtio);
}
