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Re: 9 bit serial communication




----- Original Message -----
From: "Szabo, Tamas" <Tamas.Szabo@xxxxxxx.com>
To: <dev-etrax@xxxxxxx.com>
Sent: den 6 december 2002 16:31
Subject: 9 bit serial communication


> Hello,
>
> Is there an easy way to interface ETRAX and 8051 family microcontroller on
> serial line with 9 bit communication? In 8051 there is a serial mode where
> 9th bit can signal that the 8 bits is data or address.
>
> Thx,
>
> Sza2.
>
> Problems with Windows - Reboot.
> Problems with Linux       - Be root.

I beleive the only way to solve that is to use 8 bit and control
the parity settings depending on if the 9'th bit should be high or low.

For receive, you can detect a low 9:th bit by checking for parity error.
It's possible to do this from user mode, although it might be more efficient
to add the support to the serial driver.
To detect parity error from user mode, use PARMRK flag, see 'man tcsetattr'.

I beleive someone might have created such a 9 bit driver already, try
google.

/Johan