Serial Communication debugging

[zcuba]

Hi..
I'm getting a headache, can anyone help me solve this ?
or at least throw a ptr to help me along..

I have a nerving issue with a serial port driver I have been trying to build.
First of all the hardware is connected to an usb<->RS232 adapter
it registers as a device in /dev/ as /dev/ttyUSB0

I can do:
> screen /dev/ttyUSB0

and transmit strings to the device.

In general this device will report back with a bit pattern, in a special case however it returns a char array, so I present this example.

I transmit "$MIB,RESET*87" to the device using screen
screen shows that the device responds with:

%CruizCore R1H VX. XX
%SW Ver X. XX
%(c) 2002-2009 Microinfinity Co., Ltd.

I cannot see from the screen output if the response is null terminated or not.
It is not written in the documentation either, and screen simply outputs all (typecasted) chars that comes in at ttyUSB0..

The firmware on the external hardware also outputs data using an internal timer.
this looks like mumbo-jumbo, but I expected that much as the start of the bytes and bits are more or less random, and contains integers with hex values....

well--
I attempted to reproduce the reset functionality from c++
bot I do not get the expected string as a response.
instead I get a small random amount of "mumbo jumbo"

int main()
{
	Gyro *gyro;
        //connect and reset / calibrate:
	gyro = new Gyro("/dev/ttyUSB0", 3);

}

/**
------
relevant content of gyro class:
------------------
*/

Gyro::Gyro(string path, unsigned int calibrateTime = 30) : path(path) {
	com = new CPCom(path);
	gyro_model = CRUIZCORE_XG1010;

        //The UART default configuration for CruizCore xg1010 is
	//115,200 bps, 8 data bit, 1 stop bit, and no parity.

	//reset by transmitting: $MIB,RESET*87
	unsigned char cmd[14];
		cmd[0] = '$';
		cmd[1] = 'M';
		cmd[2] = 'I';
		cmd[3] = 'B';
		cmd[4] = ',';
		cmd[5] = 'R';
		cmd[6] = 'E';
		cmd[7] = 'S';
		cmd[8] = 'E';
		cmd[9] = 'T';
		cmd[10]= '*';
		cmd[11]= '8';
		cmd[12]= '7';
		cmd[13]= '\0';
		int len;
		int r;
                //printf("%s\n", cmd);
		this->com->cpwrite(cmd, 13);
		this->com->cpflush();

		printf("The procedure will take ~4 seconds\n\n");
		usleep(4000000);

		//init tmp string to null
		unsigned char response[142];
		response[0] = '\0';

		//to avoid a printf reading random memory if read returns non null terminated strings
		response[141] = '\0';

		r = this->com->cpread(response, 140);
		this->com->cpflush();
		if(r > 0)
		{
			printf("%s\n has been reset and calibrated\n", response);
		}
}

Gyro::~Gyro() {
	delete com;
}

/**
relevant part of com class:
*/

CPCom::CPCom(const string comPortPath) {
  this->_cph = open(comPortPath.c_str(), O_RDWR | O_NOCTTY);

  if (this->_cph == -1){ //Opening of port failed
    cout << "Unable to open IMU com port " << comPortPath << endl << "Errno = " << errno << endl;
	printf("error:%s\n",strerror(errno));
    return;
  }
  
  //Get the current options for the port...
  struct termios options;
  tcgetattr(this->_cph, &options);

  //set the baud rate to 115200
  int baudRate = B115200;
  cfsetospeed(&options, baudRate);
  cfsetispeed(&options, baudRate);

  //set the number of data bits.
  options.c_cflag &= ~CSIZE;  // Mask the character size bits
  options.c_cflag |= CS8;

  //set the number of stop bits to 1
  options.c_cflag &= ~CSTOPB;

  //Set parity to None
  options.c_cflag &=~PARENB;

  //set for non-canonical (raw processing, no echo, etc.)
  options.c_iflag = IGNPAR; // ignore parity check close_port(int
  options.c_oflag = 0; // raw output
  options.c_lflag = 0; // raw input

  //Time-Outs -- won't work with NDELAY option in the call to open
  options.c_cc[VMIN]  = 0;   // block reading until RX x characers. If x = 0, it is non-blocking.
  options.c_cc[VTIME] = 100;   // Inter-Character Timer -- i.e. timeout= x*.1 s

  //Set local mode and enable the receiver
  options.c_cflag |= (CLOCAL | CREAD);

  //flush serial port buffers
  this->cpflush();

  //Set the new options for the port...
  int status = tcsetattr(this->_cph, TCSANOW, &options);

  if (status != 0){ //For error message
    cout << "Configuring comport failed with status error = " << status << endl;
    return;
  }

  //flush serial port buffers
  this->cpflush();
}


CPCom::~CPCom() {
  close(this->_cph);
}


bool CPCom::cpflush() {
  if ( tcflush(this->_cph,TCIOFLUSH) == -1 ){
    cout << "IMU Flush Failed" << endl;
    return false;
  }
  return true;
}


int CPCom::cpread(unsigned char* bytes, int bytesToRead) {
	int r = read(this->_cph, bytes, bytesToRead);
	if(r == -1)
	{
		printf("error:%s\n",strerror(errno));
	}
	return r;
}


int CPCom::cpwrite(unsigned char* bytes, int bytesToWrite) {
  return write(this->_cph, bytes, bytesToWrite);
}

[mikeofthenight]

If you have root privileges and I am assuming your on a linux box. You could try as root

tail -f /var/log/messages

This will display and update your messages logfile actively. So you could then run your program and watch at the same time
for any messages relating to your program.