8051 64K external SRAM possible?

Started by andrew queisser February 20, 2004
I'm planning to add some external SRAM to my 8051.
I've seen many examples how to add 32K but never 64K.
Is it possible to have the full external data space in SRAM?
If so, do I just hardwire the CE line to always select the
chip?

Thanks,
Andrew



andrew queisser wrote:
> I'm planning to add some external SRAM to my 8051. > I've seen many examples how to add 32K but never 64K. > Is it possible to have the full external data space in SRAM?
Of course.
> If so, do I just hardwire the CE line to always select the > chip?
Yes. ( and WRN -> WEN and RDN -> OEN )
>I'm planning to add some external SRAM to my 8051. >I've seen many examples how to add 32K but never 64K. >Is it possible to have the full external data space in SRAM? >If so, do I just hardwire the CE line to always select the >chip? > >Thanks, >Andrew
Yes there is no problem with using the full 64K for SRAM. The reason that people often use 32K is that 32K chips are cheaper and secondly, it keeps some memory space for mapping external peripherals such as A/D chips etc.
"andrew queisser" <andrew.queisser@hp.com> wrote in message
news:<4036868a$1@usenet01.boi.hp.com>...
> I'm planning to add some external SRAM to my 8051. > I've seen many examples how to add 32K but never 64K. > Is it possible to have the full external data space in SRAM? > If so, do I just hardwire the CE line to always select the > chip? > > Thanks, > Andrew
I've done banking with 6811s with up to 1M of space. Works well for static kind of memory, but puts some trickery in the code. Hopefully your compiler supports it.
In article <4036868a$1@usenet01.boi.hp.com>, andrew queisser
<andrew.queisser@hp.com> writes
>I'm planning to add some external SRAM to my 8051. >I've seen many examples how to add 32K but never 64K. >Is it possible to have the full external data space in SRAM? >If so, do I just hardwire the CE line to always select the >chip?
Of course it is possible. P0 and P2 give 16 address lines. You are adding XDATA which is 64K external data. This is a seperate space to the iData and Data. (though confusingly some 51]s have "internal xdata" that is an additional space.) There is a description of this in thje C51 Primer at Http://Quest.phaedsys.org /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ \/\/\/\/\ Chris Hills Staffs England /\/\/\/\/\ /\/\/ chris@phaedsys.org www.phaedsys.org \/\/ \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/