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MOTOROLA
Chapter 23. Development Support
23-41
Development Port
Figure 23-12. Download Procedure Code Example
For large blocks of data this sequence may take significant time to complete. The “fast
download procedure” of the debug port may be used to reduce this time. This time
reduction is achieved by eliminating the need to transfer the instructions in the loop to the
debug port. The only transactions needed are those required to transfer the data to be placed
download procedure”.
Figure 23-13. Slow Download Procedure Loop
Figure 23-14. Fast Download Procedure Loop
The sequence of the instructions used in the “fast download procedure” is the one illustrated
in
Figure 23-12 with RX = r31 and RY = r30. This sequence is repeated infinitely until the
“end download procedure” command is issued to the debug port.
Note that, the internal general purpose register 31 is used for temporary storage data value.
Before beginning the “fast download procedure” by the “start download procedure
command”, The value of the first memory block address, – 4, must be written to the general
purpose register 30.
INIT:
Save RX, RY
RY <- Memory Block address- 4
...
repeat: mfspr
RX, DPDR
DATA word to be moved to memory
stwu
RX, 0x4(RY)
until here
...
Restore RX,RY
External
MFSPR
DATA
STWU
Transaction
Internal
Activity
External
DATA
Transaction
Internal
Activity