User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 188
www.energymicro.com
MB bank can be accessed. From data space either four 64 MB banks (when ALTMAP bit is 0) or four
256 MB banks (when the ALTMAP bit is 1) can be accessed as shown in Figure 14.23 (p. 188) and
Figure 14.24 (p. 189) respectively.
The EBI regions starting at address 0x80000000 in the memory map of the EFM32GG can also be used
for code execution. When running code via EBI regions starting at this address, the Cortex-M3 uses
the System bus interface to fetch instructions. This results in reduced performance as the Cortex-M3
accesses stack, other data in SRAM and peripherals using the System bus interface. Code accesses
via the System bus interface will not be cached. Furthermore, it should be noted that the address area
from 0xA0000000 to 0xC0000000 is marked NX (no-execute) by default. To be able to run code via
the EBI efficiently, the EBI is also mapped in the code space at address 0x12000000. When running
code from this space, the Cortex-M3 fetches instructions through the I/D-Code bus interface, leaving
the System bus interface for data access. Instructions fetched via the I/D-Code bus interface can be
cached to increase performance. The EBI regions mapped into the code space can however only be
accessed by the CPU, i.e. not the DMA.
Depending on the setting of the ITS bitfield in the EBI_CTRL register. The external device behavior,
including for example data width, timing definitions, page mode operation, and pin polarities, is either
defined for all banks at once or individually per bank.
Figure 14.23. EBI Default Memory Map (ALTMAP = 0)
EBI Region 0 (32 MB)
Code
0x0 00000 00
0x1 fffffff
0x2 00000 00
0x7 fffffff
0x1 20000 00
EBI Region 1 (32 MB)
EBI Region 2 (32 MB)
0x1 3ffffff
0x1 40000 00
0x1 5ffffff
0x1 60000 00
0x1 7ffffff
0x1 80000 00
0x1 fffffff
EBI Region 3 (128 MB)
EBI Region 0 (64 MB)
0x8 00000 00
EBI Region 2 (64 MB)
EBI Region 1 (64 MB)
0x8 3ffffff
0x8 40000 00
0x8 7ffffff
0x8 80000 00
0x8 bffffff
0x8 c0 0 0000
0x8 fffffff
EBI Region 3 (64 MB)
EBI Regions
0x8 00000 00
0xbfffffff
0xc0000 000
0xffffffff
0x1 20000 00
0x8 fffffff