Graphical LCD Display:

An accurate and simple graphical oscilloscope using a PIC18F2550 microcontroller and an AGM1264F graphical LCD has been constructed using the PIC18F2550 GLCD Text Test as basis. It has the capability of measuring the maximum voltage, peak-to-peak voltage, average voltage, minimum voltage, and the zero-crossing frequency for a DC signal over 100 samples. To capture on rise or fall, the oscilloscope has a built-in edge trigger function that can be set.

Using the change Time Division function, the time scale for the display is variable and can be easily redefined while the voltage range can be changed to 0-5V, 0-2.5V, and 0-1.25V. The relatively slow acquisition time and sampling rate is the main limitations of this oscilloscope due to the fact that the inputs are limited by the constraints of the internal ADC.
A 9V battery is used as the power supply along with a high-accuracy low drop-out linear voltage regulator to provide a stable 5V supply for the microcontroller and the graphical LCD. The power spikes/ripples are prevented by capacitor.