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Re: ISA bus type in etrax


Do you want the ETRAX chip to be the master on the ISA bus ?
It is possible to do that but it is not straight forward.
The ISA bus is a very slow bus and there is not wait state configuration
possibilities enough to get all timing long enough. Therefore you need
external glue logic to generate read and write strobes etc. and need to
use the WAIT_ input of the ETRAX chip to make the cycles long enough.

You may get problems with the Ethernet interface if it runs at 100
Mbit/s, because the ISA accesses lock up the bus so long that you may get 
FIFO overrun/underrun. With 10 Mbit Ethernet this should be no problem.
There is a way to design around that, with use of the RERUN_ pin,
but then the glue logic becomes really complicated, and nobody has 
ever used this possibility in any real application.

Per Zander                      email: per.zander@xxxxxxx.com
Axis Communications AB          Tel:   +46 46 272 18 25 
Emdalavagen 14                 Fax:   +46 46 13 61 30
SE-223 69 LUND, SWEDEN          Visit our web site: http://www.axis.com/

On Fri, 17 Jan 2003, Saiful wrote:

> Hi,
> Can I interface ISA bus to etrax chip.
> Saiful