Multimeters are a wonderful and easy-to-use tool to accurately quantify the incoming AC voltage from a pure sine wave output power supply. Barring a few high-end hybrid models, not all are capable of plotting the trend of this quantity over a limited time period, like an oscilloscope. So, I decided to build a voltage monitoring system with RTOS.
I’m a digital clock nut. I began experimenting with the newer Nextion displays, which I really like. I’ve produced digital clock versions for the 3.5, 5, and 7 inch size Nextion display. They all run from the same printed circuit board and have several different functions.
After creating an Internet connected digital clock using the Adafruit RA8875 driving an seven inch LCD display, I decided to step it up a notch and add several additional features including: the ability to set an alarm; a countdown timer for uses like monitoring an exercise program; a weather display to provide brief conditions at 10 different cities; a real time stock market report that gives the changing prices for a selection of stocks; and lastly (just for fun), a Mandelbrot fractal generator to produce those wonderful images.
