termios with high baud rate...

[Stan]

----- Original Message ----- 
From: "Chris Caudle" <chris at chriscaudle.org>
To: "rtems-users" <rtems-users at rtems.com>
Sent: Thursday, January 15, 2004 9:00 PM
Subject: Re: termios with high baud rate...


> > I don't receive characters if the flow is continuous :(
>
> This sounds similar to problems I have had in the past where the baud
rates at each end were not quite the same, but were > close enough to work
for short periods of time.

I don't think, because I tested without to use the termios ( in polled
mode ), it working well.

> Grab an o'scope and verify that the baud rate on your 5206 board, and
whatever device is attached at the other end (PC?).
>
> I don't have a 5206 based board, but looking over the documentation, it
appears that the processor is running at 25MHz,
> and the UART clock is derived from that by a divider.

    I use 5206e Coldfire at 50 MHz.

> The baud rate clock runs at 16x the serial line rate, so for 115200, you
need a 1.8432MHz clock.
> If you have a 25MHz clock as the input to the divider, you can use a
divisor of 13 and get 1.9231MHz clock, or a divisor of 14 and get a
1.7857MHz clock.
> The first is about 5% above nominal, the second is about 5% below nominal.
> That is pretty close to the nominal bit rate, so your problem may not be
related, but should be something you consider.

Thanks for your ideas...
Stan.

>
> -- Chris Caudle
>
>