DSP56303 FREESCALE [Freescale Semiconductor, Inc], DSP56303 Datasheet - Page 66

• Manufacturer Part Number: DSP56303
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Core Configuration
4-8
Bit Number
23–22
21
20
19
18
17
Bit Name
CP[1–0]
RM
SM
CE
SA
Reset Value
Table 4-2. Status Register Bit Definitions
11
0
0
0
0
0
DSP56303 User’s Manual, Rev. 2
Core Priority
Under control of the CDP[1–0] bits in the OMR, the CP bits specify the priority
of core accesses to external memory. These bits are compared against the
priority bits of the active DMA channel. If the core priority is greater than the
DMA priority, the DMA waits for a free time slot on the external bus. If the core
priority is less than the DMA priority, the core waits for a free time slot on the
external bus. If the core priority equals the DMA priority, the core and DMA
access the external bus in a round robin pattern (for example, ... P, X, Y, DMA,
P, X, Y, ...).
Dynamic
Static
Rounding Mode
Selects the type of rounding performed by the Data ALU during arithmetic
operations. If RM is cleared, convergent rounding is selected. If RM is set,
two’s-complement rounding is selected.
Arithmetic Saturation Mode
Selects automatic saturation on 48 bits for the results going to the
accumulator. This saturation is performed by a special circuit inside the MAC
unit. The purpose of this bit is to provide an Arithmetic Saturation mode for
algorithms that do not recognize or cannot take advantage of the extension
accumulator.
Cache Enable
Enables/disables the instruction cache controller. If CE is set, the cache is
enabled, and instructions are cached into and fetched from the internal
Program RAM. If CE is cleared, the cache is disabled and the DSP56300 core
fetches instructions from external or internal program memory, according to
the memory space table of the specific DSP56300 core-based device.
Note:
Reserved. Write to zero for future compatibility.
Sixteen-Bit Arithmetic Mode
Affects data width functionality, enabling the Sixteen-bit Arithmetic mode of
operation. When SA is set, the core uses 16-bit operations instead of 24-bit
operations. In this mode, 16-bit data is right-aligned in the 24-bit memory
locations, registers, and 24-bit register portions. Shifting, limiting, rounding,
arithmetic instructions, and moves are performed accordingly. For details on
Sixteen-Bit Arithmetic mode, consult the DSP56300 Family Manual.
Priority
Mode
To ensure proper operation, do not clear Cache Enable mode while
Burst mode is enabled (OMR[BE] is set).
(Highest)
(Lowest)
Priority
Core
0
1
2
3
core < DMA
core = DMA
core > DMA
Determine
d by DCRn
(DPR[1–0])
for active
DMA
channel
Priority
DMA
Description
(CDP[1-0])
OMR
00
00
00
00
01
10
11
Freescale Semiconductor
SR (CP[1–0])
00
01
10
11
xx
xx
xx