RAM access

jgil · ‎2003-07-08

Posted on July 08, 2003 at 15:00

RAM access

jgil · ‎2011-05-17

Posted on May 17, 2011 at 11:54

Hi,

I have a question about memory access. IÂ´m loading the example AN1560 in evaluation board with the uPSD3234A. The memory map of my system looks something like:

Legend:

MF =Main Flash

SF=Secondary Flash

MF

==

0x8000-0xFFFF (paged )

SF

==

0x0000-0x7FFF

SRAM

====

0x2000-0x3FFF

I've a variable

XDATA char signal.

I am not able to write to the SRAM (in data space) executing from the SF. The value of setting the VM reading with KEIL debug is 0xFFH.

My understanding was that, in this case, all memory write accesses ( in the range 0x2000-0x3FFF) should be sent to the SRAM even though it has the highest priority.

Why can I not write to the SRAM? Do I need to do something more before I try to write?

I using the Keil compiler and most of my code is in 'C'.

Thanks.

joseph2399 · ‎2011-05-17

Posted on May 17, 2011 at 11:54

Please take a look at our example 2 (DK3200_2_c) of the DK3200 eval board, it uses the SRAM on the uPSD. You may want to take a look at the, USB_Test.M51, map file for a list of variables that is mapped to X:2000 - 3FFF, SRAM memory locations.