libftdi Archives

Subject: RE: Writing and reading to a FT232R

From: "Ampt,Maurice M.L." <m.ampt@xxxxxxxxxxxxxxxxx>
To: "libftdi@xxxxxxxxxxxxxxxxxxxxxxx" <libftdi@xxxxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 7 Nov 2011 14:31:47 +0100
Thank you for responding again,

    Bonnes, Uwe> As with every hardware/software/firmware setup, try to find 
the failing part.
    ....
    Bonnes, Uwe> And there may be even problems with the cables, the connectors 
or the USB port on the PC.

If I use the following code it works perfectly:

fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);
fcntl(fd, F_SETFL, 0);
if (fd == -1)
    printf("Com open failed\n");
//get the current options
tcgetattr(fd, &options);
//edit the current options
options.c_iflag = 0;
options.c_oflag = 0;
options.c_cflag = CS8 | CREAD | CLOCAL; //8n1, 8 data bits, no parity and 1 
stop bit
options.c_lflag = 0;
options.c_cc[VMIN] = 1;
options.c_cc[VTIME] = 5;
cfsetispeed(&options, B115200);   //Plugwise device I'm using communicates on a 
baudrate of 115200
cfsetospeed(&options, B115200);
//set the current options
tcsetattr(fd, TCSANOW, &options);
write(fd, message, message.length());

Doesn't that rule out the failure of hardware? 
Therefore I think it must be the code I'm using.

You also said:

    Bonnes, Uwe>  Maybe RTS/CTS or some other controlling line is in a bad 
state.

I think you could be very right here, however I sadly do not know what could be 
wrong.

However the earlier mentioned code cannot determine wether ttyUSB0 or ttyUSB1 
is the right USB device to communicate with, 
this is why I want to use libftdi.

    Bonnes, Uwe> That was the reason why I suggested the examples/testserial. 
Does that run now ?

Sadly the device I'm using doesn't write anything on its own, 
so the serial_read program does work and says read 0 bytes,
but because I can't write to it I'll never read anything and therefore do not 
know if it is working or just returning 0 all the time.

Maurice Ampt.
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