topic Re: how to set ~CS high time from MCF5280 (EIM External Interface Module)??? in ColdFire/68K Microcontrollers and Processors

how to set ~CS high time from MCF5280 (EIM External Interface Module)???

nicolai46 — Mon, 20 Oct 2008 22:58:21 GMT

Hello,

I have a problem with interfacing a dualuart ic (EXAR XR68C192) with the MCF5280.
The dualuart requires a minimum time of 100ns between to asserted chip selects.

I´ve found the option to insert wait states (chip select control register),
but this leads only to a longer chip select assert time but not a longer deassert time.

How can I extend the chip select deasert time?

Thanks,
Nicolai

Message Edited by nicolai46 on 2008-10-20 04:59 PM

Re: how to set ~CS high time from MCF5280 (EIM External Interface Module)???

admin — Tue, 21 Oct 2008 01:49:55 GMT

Well, I don't know much about MCF5280 or its EIM, but one way of solving the problem would be to wrap accesses to the XR68C192 in assembly language subroutines and supplying enough NOPs to ensure long enough CS deassert time.

Re: how to set ~CS high time from MCF5280 (EIM External Interface Module)???

nicolai46 — Tue, 21 Oct 2008 14:14:18 GMT

I still run this workaround with NOP´s but I would like to know if there is a possibility to enlarge the timing
between two CS´s with register settings of the external bus.