AN1176 STMicroelectronics, AN1176 Datasheet - Page 12

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

The following are things to notice about this simple PSDabel file (in order):
Page 10
"**** Definitions for convenience and readability
X
page = [pgr2..pgr0];
address = [a15..a0];
EQUATIONS
"******** DPLD equations ************************
" Write chip select equations to implement the memory map
fs0 = (address >= ^h0000) & (address <= ^h3FFF) & (page == 0);
fs1 = (address >= ^h4000) & (address <= ^h7FFF) & (page == 0);
fs2 = (address >= ^h0000) & (address <= ^h3FFF) & (page == 1);
fs3 = (address >= ^h4000) & (address <= ^h7FFF) & (page == 1);
fs4 = (address >= ^h0000) & (address <= ^h3FFF) & (page == 2);
fs5 = (address >= ^h4000) & (address <= ^h7FFF) & (page == 2);
fs6 = (address >= ^h0000) & (address <= ^h3FFF) & (page == 3);
fs7 = (address >= ^h4000) & (address <= ^h7FFF) & (page == 3);
ees0 = (address >= ^hC000) & (address <= ^hDFFF) & (page == X);
ees1 = (address >= ^hE000) & (address <= ^hFFFF) & (page == X);
ees2 = (address >= ^h0000) & (address <= ^h1FFF) & (page == 4) ;
ees3 = (address >= ^h2000) & (address <= ^h3FFF) & (page == 4) ;
rs0 = (address >= ^h8200) & (address <= ^h89FF) & (page == X);
csiop = (address >= ^h8A00) & (address <= ^h8AFF) & (page == X);
"******** GPLD/ECSPLD Equations ***************
" Write equations for general logic and external chip
" select equations here. See Application Notes 55 and 57
" for details.
end
The pin declarations for connection to the 68HC11 occur at the beginning of the file.
No PSD general-purpose I/O pins are declared in this example for simplicity. These
features can be easily implemented, see App Notes 55 & 57 for examples using I/O pins.
Internal PSD nodes are declared for memory selection and PSD control.
Some logic definitions are stated to make the file more readable.
The HDL equations appear for the selection of internal PSD memory segments and the
PSD control register. Each memory segment is assigned to an address range according to
the memory map of Figure 4.
Observe how the page register is used to participate in memory selection.
No equations for the GPLD are used here. See App Notes 55 & 57 for examples.
= .x.;
"Don't care symbol
"page symbol based on three page bits
"De-muxed MCU address signals