Wrapper
Address
Data
POM
Address
Data
EMIF
SCR
Program
Memory
External
Memory
(overlay)
ext.
Mem Bus
Internal
RAM
Introduction
673
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Parameter Overlay Module (POM)
18.1.3 Block Diagram
Figure 18-1. System Overlay Block Diagram
18.2 Module Operation
The POM has up to 32 programmable regions. Whenever the CPU requests data from the non-volatile
memory which address falls into one of the programmed regions, the POM will request the data from the
overlay memory. Wait states will be automatically inserted until the data is available from the overlay
memory. This ensures that the overlay memory has the same (in the case that the latency from overlay
memory is less than the program memory latency) or slower access time than the program memory.
The POM does not provide a feature to write into the overlay memory. The write has to be performed
directly to the memory mapped address space of the overlay memory.
When the module is disabled, no redirection of access will be performed.
NOTE:
The overlay feature is not available for any other bus masters other than the main CPU. Any
attempt to access overlaid memory via the POM by any other bus master would result in a
deadlock situation (system hang). Other bus masters need to access the target internal or
external memory directly.