PC-Based Logic Analyzer

ABSTRACT

The study aimed to develop a PC-Based Logic Analyzer with 8-bit Patter Generator for the Electronics Laboratory of the College of Engineering of Central Philippine University. The researchers decided to develop the system based on the following problems: (1) lack of PC-Based Logic Analyzer in the laboratory; (2) the difficulty of students and professors doing logic system related experiments to capture, generate, and display high-speed and large amount of digital signals using the ordinary logic trainers and the oscilloscope; (3) and the expensive cost (ranges from P 60,000 to P 375,000) of commercially available PC-based logic analyzers. The researchers developed a logic device under test board (DUT board), where logic circuit are tested, and interfaced the board to the PC through the line printer port (parallel port). The technique used the capabilities of the computer’s parallel port to provide an 8-bit input. A buffer circuit was also constructed to protect the system from damage. The logic analyzers’ program controls the operation of the logic analyzer. The software that provides the interface was written using Matrix Laboratory (MATLAB). Overall, the logic analyzer has the capacity to capture and generate (basic requirements when testing logic circuits) large amount of digital signals. When capturing signals, a +5V input signal is represented by logic 1 (High) and a -5Vsignal is represented by the logic 0 (Low). The frequency is measured with respect to the actual cycle time, in which frequency is inversely proportional to the actual cycle time, in which frequency is inversely proportional to the cycle time. In signal generation, the functionality of the logic circuit under test was tested by the setting (through the analyzers’ user interface) a specific bit pattern and then injected into the circuit. Light emitting diodes (LED) are used to verify the results. If logic 1, LED is on and logic 0, LED is off.