AN1176 STMicroelectronics, AN1176 Datasheet - Page 8

• Manufacturer Part Number: AN1176
• Description: 68HC11/PSD813F1 DESIGN GUIDE
• Manufacturer: STMicroelectronics

To make this division of the memory map possible (i.e. common upper half, paged lower half),
the 68HC11 initialization firmware must move the internal 68HC11 SRAM and registers from
their default location of 0000h, to the new location of 8000h, as shown in Figure 4. There is a
special register in the 68HC11 (the INIT register) that facilitates this move. See the 68HC11
reference manual from Motorola. This move is necessary to “clean-up” the memory map,
meaning that the entire region from 0000h – 7FFFh is free to use for paging, once these internal
MCU locations are moved up and out of the way to 8000h. Also note that the common area (non-
paged) had to be located in the upper half of memory (8000h – FFFFh) because the 68HC11
boots from high memory (FFFEh).
The nomenclature FS0-FS7, EES0-EES3, RS0, and CSIOP in Figure 4 refer to the internal
memory segments of the PSD. The main flash memory has eight 16K byte segments (FS0-FS7).
The EEPROM has four 8K byte segments (EES0-EES3). The 2K byte SRAM has a single
segment (RS0). The internal PSD control registers lie in a 256-byte address space, named
CSIOP. You place these PSD memory elements to the desired location within the memory map
by writing Hardware Description Language (HDL) equations for the Decode PLD for each
memory segment. Equations are written and compiled in the PSDsoft software development
environment, using the standard Hardware Description Language, ABEL (called “PSDabel” as
packaged in PSDsoft).
Note that the page register bits are zero at power-up or after a system reset.
2.3 PSDsoft Design Entry
Highlights of design entry will be given here. Please refer to Application Note 57 for a thorough
coverage of all the features of PSDsoft. This section is meant to show you just the essentials to
get you going. Here are the steps:
2.3.1 Invoke PSDsoft and Open a New Project
Now you have your project established, based on a PSD813F1 and a 68HC11.
Page
6
Start PSDsoft.
Open a new project.
Enter your project name and directory (in this example, it is named ‘yourfile’ in the
directory PSDSOFT\YOUR_PROJECT).
Select a PSD813F1
Select the 68HC11 template
Click OK.