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RE: I need to configure serial port to send 5 bit characters




The ETRAX 100LX supports baud rates down to 48 baud, but the 
'standard baud rates' only range down to 300 baud. If you want 
to go lower, you need to use another internal baud rate generator.
It seems like the linux driver doesn't have support for that.

Note! The old ETRAX 100 doesn't support baud rates below 300 baud.
The possibility to have lower baud rates was added in ETRAX 100LX. 

See ETRAX 100LX designer's reference chapter 12.5 for more information.

Per Zander

On Fri, 4 Oct 2002, Henry Minsky wrote:

> 
> OK, this trick worked for sending characters, however I have another 
> problem which
> is that the B75 baud rate (75 baud) does not seem to work.
> 
> I am using cfsetospeed with B75 but the baud still seems to be 9600 coming 
> out of
> the serial port.
> 
> Is 75 baud not supported by the UART? Is there a way to manually set the 
> baud rate
> divisor from a user program?
> 
> Thanks,
>          Henry
> 
> 
> 
> 
> At 09:27 AM 10/4/2002 +0200, gerhard@xxxxxxx.at wrote:
> 
> >Hello,
> >
> >even when the hardware does not support 5 bits (and that's a fact) you can 
> >send
> >5 bit characters using a simple trick:
> >
> >1. Configure the serial port for 8 data bits
> >2. Take your character and shift it left by 3
> >3. Set the 3 lowest bits to 1
> >4. Send it out
> >
> >This should basically work, but you have o live with some limitations.
> >
> >- Between two characters you have now 3 more stop bits, this means that you
> >cannot send at the full data rate
> >- This works only on transmitting. When you want that receiving works the 
> >same
> >way you must ensure that the opposite system inserts also some pause time
> >between two characters, and you have to mask off the "unused stop bits".
> >
> >Hope this may work for you,
> >Gerhard
> 
> 
>