Posted on February 21, 2007 at 08:03We are working with the STPC Atlas in Local Bus mode, and we've faced the following situation regarding the FCS0 and FCS1 Memory Spaces provided by the STPC Atlas.
We use the STPC Atlas booting from a 256 KB 8bit flash addressed through FCS0. In order to achieve this, we set the corresponding strap option (pull-down on SDRAM_MD36). The system boots ST's primary loader, and in this primary loader we try to configure the FCS1 address space with a memory space of 16 MBytes, so the lower 8MBytes are addressed through FCS1L# and the upper 8MBytes are addressed through FCS1H# (this is what we understand reading the documentation regarding FCS1 configuration).
However, with this configuration (16 MBytes of memory space in FCS1) what we can see is that only FCS1L# is activated for the entire memory map, and FCS1H# is never being activated. If we change the memory space to 32 MBytes, we can see that the lower 16MBytes are addressed with FCS1L# and the upper 16MBytes are addressed using FCS1H#.
So, we don't understand why the behaviour of FCS1L# and FCS1H# is different depending on the size of the memory space configured to FCS1. Although we could work with the 32 MByte memory space configuration, the best option for us would be the 16 MByte memory space configuration so we don't have alias between our elements in the address space.
Does anybody know the reasons for this behaviour? Did we misunderstood the datasheet information?
Thanks in advance for your attention,
