dsp56000 Freescale Semiconductor, Inc, dsp56000 Datasheet - Page 571

• Manufacturer Part Number: dsp56000
• Description: 24-bit Digital Signal Processor Family Manual
• Manufacturer: Freescale Semiconductor, Inc

A.9
Due to the pipelined nature of the DSP56K central processor, there are certain instruc-
tion sequences that are forbidden and will cause undefined operation. Most of these
restricted sequences would cause contention for an internal resource, such as the stack
register. The DSP assembler will flag these as assembly errors.
Most of the following restrictions represent very unusual operations which probably
would never be used but are listed only for completeness.
Note: The DSP56K macro assembler is designed to recognize all restrictions and flag
them as errors at the source code level. Since many of these are instruction sequence
restrictions, they cannot be flagged as errors at the object code level such as when using
the DSP56K simulator’s single-line assembler. Therefore, if any changes are made at
the object code level using the simulator, the user should always re-assemble his pro-
gram at the source code level using the DSP56K macro assembler to verify that no
restricted instruction sequences have been generated.
MOTOROLA
Note 1: wx = external X memory access wait states
Note 2: wx, wy, wp, and wio are programmable from 0 - 15 wait states in the port A bus control register (BCR).
X:
X:
Y:
Y:
P:
P:
I/O:
I/O:
L: XY:
L: XY:
L: XY:
L: XY:
Access
Type
INSTRUCTION SEQUENCE RESTRICTIONS
wy = external Y memory access wait states
wp = external P memory access wait states
wio = external I/O memory access wait states
Access
X Mem
Ext
Ext
Ext
Int
Int
Int
—
—
—
—
—
—
Table A-14 Memory Access Timing Summary
Access
INSTRUCTION SEQUENCE RESTRICTIONS
Y Mem
Ext
Ext
Ext
—
—
Int
—
—
—
—
Int
Int
Freescale Semiconductor, Inc.
For More Information On This Product,
INSTRUCTION SET DETAILS
Access
P Mem
Ext
Int
—
—
—
—
—
—
—
—
—
—
Go to: www.freescale.com
Access
I/O
Ext
Int
—
—
—
—
—
—
—
—
—
—
Cycle
+ ax
wx
—
—
—
—
—
—
—
—
—
—
0
Cycle
+ ay
wy
—
—
—
—
—
—
—
—
—
—
0
Cycle
+ ap
wp
—
—
—
—
—
—
—
—
—
—
0
Cycle
+ aio
wio
—
—
—
—
—
—
—
—
—
—
0
2 + wx + wy
Cycle
+ axy
A - 305
wy
wx
—
—
—
—
—
—
—
—
0