CC1110Fx / CC1111Fx
11.2 Memory
The 8051 CPU architecture has four different
memory spaces. The 8051 has separate
memory spaces for program memory and data
memory. The 8051 memory spaces are the
following (see section 11.2.1 and 11.2.2 for
details):
CODE.
A 16-bit read-only memory space for
program memory.
DATA.
An 8-bit read/write data memory
space, which can be directly or indirectly,
accessed by a single cycle CPU instruction,
thus allowing fast access. The lower 128 bytes
of the DATA memory space can be addressed
either directly or indirectly, the upper 128 bytes
only indirectly.
XDATA.
A 16-bit read/write data memory
space, which usually requires 4 - 5 CPU
instruction cycles to access, thus giving slow
access. XDATA assesses is also slower in
hardware than DATA accesses as the CODE
and XDATA memory spaces share a common
bus on the CPU core (instruction pre-fetch
from CODE can not be performed in parallel
with XDATA accesses).
SFR.
A 7-bit read/write register memory
space, which can be directly accessed by a
single CPU instruction. For SFRs whose
address is divisible by eight, each bit is also
individually addressable.
The four different memory spaces are distinct
in the 8051 architecture, but are partly
overlapping in the
CC1110Fx/CC1111Fx
to ease
DMA transfers
operation.
and
hardware
debugger
How the different memory spaces are mapped
onto the three physical memories (8/16/32 KB
flash program memory, 1/2/48 KB SRAM, and
hardware registers (SFR, radio, I
2
S, and USB
(
CC1111Fx
)) is described in sections 11.2.1 and
11.2.1 Memory Map
This section gives an overview of the memory
map.
Both the DATA and the SFR memory space is
mapped to the XDATA and CODE memory
space as shown in Figure 14, Figure 15, and
spaces are mapped identically), and
CC1110FX/CC1111FX
has what can be called a
unified memory space.
Mapping all the memory spaces to XDATA
allows the DMA controller access to all
physical memory and thus allows DMA
transfers between the different 8051 memory
spaces. This also means that any instruction
that read, write, or manipulate an XDATA
variable can be used on the entire unified
memory space, except writing to or changing
data in flash.
Mapping all memory spaces to the CODE
memory space is primarily done to allow
program execution out of the SRAM/XDATA.
SWRS033E
Page 42 of 239
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