MMDSP Debugger 9
©1989-2019 Lauterbach GmbH
CPU specific Implementations
Breakpoints
There are two implementations for breakpoints:
• Software breakpoints
• On-chip breakpoints
For MMDSP it is only possible to set breakpoints when the clock is stopped. This applies to both software
and on-chip breakpoints.
Software Breakpoints
In order to stop the program execution at a selected instruction, the code at the break location is patched by
a software break instruction. If the software break instruction comes to the execution stage of the
pipeline, the program execution is stopped and the debug mode becomes active.
Software breakpoints can be set to instructions in RAM and with some preparations also to instructions in
FLASH (see FLASH.Create and FLASH.AUTO). Software breakpoints on instructions in FLASH should
only be used, if the number of on-chip breakpoints is insufficient.
The number of software breakpoints is unlimited.
STN8810A (Audio): note that modifications to the program memory like setting and removing a SW
breakpoint require to flush the instruction cache to guarantee that the CPU sees the updated data. This
cache flush is executed before program execution is resumed. To avoid these cache flushes resort to on-
chip breakpoints. The STN8810V (Video) is not affected as it does not have an instruction cache.
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