AN1356 STMicroelectronics, AN1356 Datasheet - Page 15

• Manufacturer Part Number: AN1356
• Description: PSDSOFT EXPRESS AND PSD4235G2 DESIGN GUIDE
• Manufacturer: STMicroelectronics

AN1356 - APPLICATION NOTE
Figure 16. CSBOOT7 Address Range
Finally, define the external chip-select for the LCD module, “lcd_e”. This chip-select is different for two
reasons. First, it is an external chip-select that does not activate any memory element inside the PSD
because the signal “lcd_e” is output on a PSD I/O pin. And second, this chip-select requires qualifiers,
meaning that this logic signal is true only for a given MCU address range AND only when one of two other
another signals are active.
In this design, “lcd_e” is true only when the MCU presents an address in the range of 06000 to 06001h
AND when either the P51XA control signal “_wrl” is true, OR when P51XA signal “_wrh” is true. To create
this logic, enter information as shown in the screen below. Since both signals, “_wrl” and “_wrh”, are active
low as they leave the P51XA, the logical NOT operator (!) is used when they are specified as qualifiers.
Signal qualifiers may be added by parking the cursor where you want the signal name to go then just
double-click on the signal name in the list of ‘Eligible signals’.
Figure 17. Signal Qualifiers
You can click the View button at any time to see a summary. Once you are satisfied with the results, click
the Next >> button.
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