Why is 6400 baud not supported!

mensfort · 01-15-2011, 03:02 AM

Hi,

I desperately want to get away from DOS and Windows, change to Linux... however I need 6400 baud for a special dongle.

I found out my PC is working in Windows perfect at this baudrate, but in Linux it is unsupported.

termios.h seems to have no support. I'm programming in C++ and want to use 6400 baud.

With setserial software I can have a divisor of 18, then the baudrate = 115200/18 = 6400. However, I want to use it in my programs (G++) and maybe also in Dosbox until my program is completely converted to Linux... however, if Linux does NOT support 6400 baud this operating system I have to stick to MFC, which is terrible.

Who has a decent solution to this?

onebuck · 01-15-2011, 06:57 AM

Moved: This thread is more suitable in Programming and has been moved accordingly to help your thread/question get the exposure it deserves.

business_kid · 01-15-2011, 06:59 AM

Why not change the dongle design? Or are you circumventing proprietary code?

wje_lq · 01-15-2011, 10:04 PM

Quote:

Originally Posted by business_kid

are you circumventing proprietary code?

We don't need to know the answer to this question, because what mensfort needs to do here is the same, regardless of whether he's circumventing proprietary code.

I found a hint here. I haven't tested the following code, but it ought to compile in both Microsoft(spit)(R) and Linux environments. Will something like this do the trick?

Code:

#if defined(__GLIBC__)
#include <asm/ioctls.h>
#include <linux/serial.h>
#endif

/* ... */

#if defined(__GLIBC__)
struct serial_struct cheerios;
#endif

/* ... */

#if defined(__GLIBC__)
if(ioctl(your_file_descriptor_here,TIOCGSERIAL,&cheerios))
{
  /* Handle error here. */
}
cheerios.flags&=(~ASYNC_SPD_MASK);
cheerios.flags|=(ASYNC_SPD_CUSTOM);
cheerios.custom_divisor=(115200/6400);
if(ioctl(your_file_descriptor_here,TIOCSSERIAL,&cheerios))
{
  /* Handle error here. */
}
#else
/* Do whatever one does in the Microsoft(spit)(R) world. */
#endif

The link mentioned above hints that before you use TIOC[GS]SERIAL, you should call tcsetattr() and set c_cflag to B38400. I'm not convinced that this is necessary, but if the above code doesn't work by itself, try adding this additional stuff first.

Hope this helps.