Default settings for IrDA discovery (baud, bits, stop, parity, flow control, etc)

Question

I'm attempting to write a tool that uses IrDA to communicate with Uwatec dive computers...on a Mac. The USB IrDA device I'm using provides a serial device (/dev/cu.IrDA-IrCOMM0 and /dev/tty.IrDA-IrCOMM0) that can be used to send and receive data. Unfortunately, the Mac does not provide an IrDA socket layer.

I've confirmed using the command line tool that shipped with the device driver that it can listen and receive IrDA communications from other devices. However, while the command line tool tells me it is communicating at 9600 baud, the rest of the settings (bits, stop bit, parity, flow control, etc) are not presented back to me.

I've tried writing my own program to listen to the data, but it is unable to receive any data and I believe the reason is because these settings are not correct. So, assuming that I'm just trying to listen to the 9600 baud IrDA discovery packets that are being sent around, what are the other settings I need to use?

If it helps, here's the snippet of code I'm currently using to set the communication parameters -- which doesn't work:

#define DEVICE "/dev/cu.IrDA-IrCOMM0"

int main(void) {
    FILE *device;
    struct termios ttystate;

    device = fopen(DEVICE, "rw");

    //get the terminal state
    tcgetattr(fileno(device), &ttystate);
    //turn off canonical mode and echo
    ttystate.c_lflag &= ~(ICANON | ECHO);
    //minimum of number input read.
    ttystate.c_cc[VMIN] = 1;

    cfsetspeed(&ttystate, B9600); // Set 9600 baud····
    ttystate.c_cflag |= (CS8 | // Use 8 bit words
                         PARENB   | // parity enable
                         PARODD   | // odd parity
                         CCTS_OFLOW | // CTS flow control of output
                         CRTS_IFLOW);// RTS flow control of input

    //set the terminal attributes.
    tcsetattr(fileno(device), TCSANOW, &ttystate);
    return EXIT_SUCCESS;
}

tommyk tommyk · Accepted Answer · 2012-10-01T12:55:18

Below is the IrDA initialization code I used for EXAR XR17C15 on Linux. Additionally you have to set baudrate as its not set in this example. I hope this helps.

//
// Set up IrDA hardware interface through UART

bool CeIrDA::SetupIrDA()
{
    struct termios termios;
    tcgetattr(hComPort, &termios);
    cfmakeraw(&termios);

    termios.c_iflag = IGNPAR;
    termios.c_oflag = 0;
    termios.c_cc[VTIME] = 1;    // timeout in 0.1s between 2 characters
    termios.c_cc[VMIN] = 1;     // min # of characters

    tcsetattr(hComPort, TCSANOW, &termios);

    xrioctl_rw_reg input;
    struct timespec delay = {0, 500};
    struct timespec delayrem;
    //EFR: Allowing Enhanced Functions and RTS/DTR flow control
    input.reg=0x09;
    input.regvalue=0x50;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);

    //MCR: Flow control RTS enabled
    input.reg=0x04;
    input.regvalue=0x40;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);

    //MCR: RTS pin high
    input.reg=0x04;
    input.regvalue=0x00;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);

    //MCR: RTS pin low
    input.reg=0x04;
    input.regvalue=0x02;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);

    //MCR: Infrared Mode
    input.reg=0x04;
    input.regvalue=0x42;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);

    //EFR: Allowing Enhanced Functions and RTS/DTR flow control
    input.reg=0x09;
    input.regvalue=0x40;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);

    //LCR: Allowing changes of DLL and DLM
    input.reg=0x03;
    input.regvalue=0x80;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);

    //DLL: Speed configuration
    input.reg=0x00;
    input.regvalue=0x02;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);

    //DLM: Speed configuration
    input.reg=0x01;
    input.regvalue=0x00;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);

    //LCR: configuration for parity, word length....
    input.reg=0x03;
    input.regvalue=0x03;
    ioctl(hComPort,WRITE,&input);

    nanosleep(&delay, &delayrem);
    return true;
}

Default settings for IrDA discovery (baud, bits, stop, parity, flow control, etc)

1 Answers