• Table of Contents

14.3 Internal Resource Remapping

The internal register block, SRAM, EEPROM, and flash memory have default locations within the 64-kB standard address space — a callback to chapter 1:

Figure 1.2 9S12 Memory Map.

• These can be reassigned to other locations during program execution by setting bits in mapping registers: INITRG, INITRM, and INITEE.
• These registers can be written only once in normal operation modes. It is advisable to explicitly establish these resource locations during the initialization phase of program execution.

If conflict occurs when mapping resources, the register block will take precedence over other resources.

Figure 14.1 Mapping precedence.

Register Block Mapping

The register block (1- or 2-kB) can be remapped to any 2-kB space within the first 32-kB of the system address space. The INITRG register can be written into once in normal mode, but many times in special modes.

Figure 14.2 Contents of the INITRG register.

In the memory map, at reset, the address space is from $0000 to $03FF.

Figure 14.3 Address of the memory map.

As noted, the register space is mappable to any 2-kB space. Using the INITRG register, it modifies upper five bits of the 16-bit register address. For reference:

• Example

SRAM Mapping

Similarly, the SRAM can be remapped to any 2-kB boundary within the 64-kB memory space. The remapping is controlled by the INITRM register.

Figure 14.4 Contents of the INITRM register.