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Ex-Bit =1 in linker.cmd

Started by horba77 July 30, 2003
Hello,
I'm trying to build a stand-alone application that processes a lot of
data that has to be stored in external data memory. I plan on using
about 4MB of external data memory by expanding the 16bit address space
with 5 GPIOs. My problem is that I do not understand how to setup the
linker.cmd file for this.
At the moment I'm programming the DSP56F807EVM with CW 5.2 and SDK
3.0. As I understand the ExtRam-Target is only for development
purposes and not what I'm looking for anyway since I want my program
to be located in internal memory. As for the Flash-Target I see that
there is a ExRam segment but I want to use the whole of the 64k
adress-space and not only what is left after stack, peripherals etc.
have been allocated.
I guess I can solve this problem by setting the Ex-Bit in the OMR-
register in order to access the entire 64k of external memory. Does
this mean that I have to change the EX-Bit all the time when I want
to upload this data to the PC?

- in order to upload the data from external data memory to the PC do
I really need to read every single word into a ALU-register, change
the Ex-Bit to 0 and then write it to the on-chip peripheral memory
for the SCI?

- could anybody send or post a linker.cmd file where EX-Bit=1?
in all the linker.cmd files I have seen the EX-Bit is always = 0

- is there a SDK function that I can use to access external memory

I appreciate any comments or examples of how to do this.
Thanks
hans