What are the MMD signals and how are they used?

The MMD* signals allow for a low-cost method of decoding the ARM memory signals.

When the ARM memory signals go into the ETM, they are latched, and then output with an MMD prefix. You can write some decode logic to look for certain memory accesses of interest. This decode logic can be used to assert the MMDIN inputs to the ETM when a certain access is made. These MMDIN inputs can then be factored into the ETM’s triggering and filtering logic to alert the ETM to certain ARM memory accesses.