8xx SCC and SMC uart latency

[Eli Brin]

Hello,

We are using the FADS board and MPC860T CPU, with ELDK 2.0.2 (kernel
06-10-2002).

We have a device that communicates over RS232 at 9600 bps.  This device has
a 4 mSec timeout, i.e we have to reply in less then 4mSec.

The packets are usually small (4-6 Bytes).  We communicate successfully with
the device, but only if we change the timeout to above 10mSec.

It seems that it takes 5-8 mSec for us to reply.  This is the same if we use
SMC or SCC.  We tried to play with the MAX_IDL and the Tx/Rx buffer sized,
but with no success.

Has anyone an idea on how to minimize the uart latency?

If we use the same code on a PC (i386) we reply in 300 microSec.

Thank you, and a happy New Year
Eli Brin

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