Re: Intel 386EX embedded processor
From: Karl Olsen (karl_at_NOSPAMmicro-technic.com)
Date: 06/30/04
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Date: Wed, 30 Jun 2004 09:19:19 +0200
learner wrote:
> I am working on a small design using Intel 386EXTC processor. The
> design has a 512KB Flash and a 512KB SRAM. The processor user manual
> says "The chip-selects generated by this unit can simplify external
> "glue logic" by providing signals that can be connected directly to
> the chip-enable inputs of external
> memory and I/O devices."
>
> My question is if I am using 8bit memories, is it possible that I can
> take UCS and connect it directly to Flash that has startup information
> and CS0 to SRAM?
Yes. After reset, UCS decodes the whole address range as 8 or 16 bit, with
15 wait states. If your flash is 8 bit, you tie BS8# low. In your startup
code, you reprogram the chip selects so that UCS only covers the desired
flash range, and CS0 covers the desired SRAM range, and with the desired
number of wait states.
> Is there a necessity of glue logic?
No.
> If yeah, how can I do that using A15:A25 address lines and get the CE
> for SRAM and FLASH?
>
> Also, do I need a 50MHz external oscillator that will be the input at
> pin clk2 for 25MHz operation of processor?
Yes.
Karl Olsen
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