Re: parallel eeproms and 8051

From: Tim Wescott (tim_at_wescottnospamdesign.com)
Date: 12/29/04 

Date: Wed, 29 Dec 2004 09:19:25 -0800

funkymunky wrote:

> Hi..
>
> Im new to embedded systems, iv started with the 89c51 uC. Ive never
> used a parallel eeprom with the 89c51, thought iv used a serial one
> with the i2c protocol (and had a tough time in getting the thing to
> work, using sdcc :-( ).
>
> My question is..can only a parallel eeprom be used to extend the RAM??
> seems logical, or else how would the uC generate the address on its
> own??

Only parallel EEPROMs can be used to extend the "native" RAM. Serial
EEPROMs are pretty much just nonvolatile storage devices.
>
> Also, can some part of the code be in the on-chip flash and the
> remaining in an external serial eeprom?? again, how then would the uC
> know the address to find the remaining lines of code?

Not in a serial EEPROM, unless you load the code out of the EEPROM and
into RAM for execution.
>
> Finally, could u point me to some good places where i can find info on
> interfacing the 8051 types to a serial eeprom. How about bus arch too..

Your brain. Just study the serial EEPROM data *** and think about how
to bit-bang it (or get an 8051 with an SPI port and use a compatible
EEPROM).
>
> Im googling for this info too, in case u plan to flame me for not doing
> that :-)
>
> Thanx in anticipation
>
> Mayank
> 

-- 
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com