Tutorial 10:  Virtual Programmable Logic

Programmable boolean logic can be implemented transparently to your own application as a virtual circuit using the change on PORTB interrupt. This tutorial demonstrates the use of this interrupt to implement a 4 input boolean expression inputs on PORTB<4..7> and output on PORTB<0>. The output is compared with the equivalent logic circuit.

Download FEATURE7X_Tutorial10.zip and unzip into folder <your path>\Tutorial 10

Filename Version Description
tut10.pjt 1.0 Project
tut10.asm 1.0 Assembler code
tut10.hex 1.0 Precompiled HEX
tut10.lst 1.0 Precompiled LST
tut10.vbb 1.0 Virtual Breadboard simulation

Running the Simulation

Open tut10.vbb and press RUN. Change the DIP settings until the logic shown by the equivalent circuit is true. The PIC output should equal the equivalent circuit expression. Note there is a slight delay between the equivalent circuit and the PIC, this is true of using the microcontroller to implement logic as it will not be as fast as pure logic.

Code Walk Through

Features Demonstrated

TRISB/PORTB

Change on PortB interrupt