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Development Capabilities and Interface
For large blocks of data, this sequence can take a significant amount of time to complete.
Using the fast download procedure of the debug port will reduce the amount of time by
eliminating the need to transfer the instructions in the loop to the debug port. The only
transactions needed are those used to transfer the data to be placed in the system memory.
Figure 20-13 and Figure 20-14 illustrate the benefit of using the fast download procedure.
EXTERNAL
TRANSACTION
INTERNAL
ACTIVITY
Figure 20-13. Slow Download Procedure Loop
EXTERNAL
TRANSACTION
INTERNAL
ACTIVITY
Figure 20-14. Fast Download Procedure Loop
The sequence of the instructions used in the fast download procedure is illustrated in
Figure 20-12, with RX = r31 and RY = r30. This sequence is repeated infinitely until the END
DOWNLOAD PROCEDURE command is issued to the debug port. The internal
general-purpose register 31 is used for temporary storage of the data value. Before
beginning the fast download procedure by issuing the START DOWNLOAD PROCEDURE
command, the value (of the first memory block address -4) must be written into the
general-purpose register 30. To end the download procedure, an END DOWNLOAD
PROCEDURE command must be issued to the debug port and the development tool will
send an additional data transaction. This data word will not be placed into the system
memory, but it is needed to stop the procedure.
20.5 SOFTWARE MONITOR DEBUGGER
When in debug mode disable, a software monitor debugger can use all of the development
support features defined in the core. When debug mode is disabled, all events result in
regular interrupt handling, in which the processor resumes execution in the corresponding
interrupt handler. The ICR and DER only influence the assertion and negation of the freeze
signal.
20-40
MFSPR
DATA
MPC823e REFERENCE MANUAL
STWU
DATA
MOTOROLA
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