Raspberry Pi based LED bar graph display is a relatively simple circuit. It can be easily built using commonly available components. For Arduino version click here. 8 LEDs, 1k potentiometer, ADS1015 ADC module and Raspberry Pi board is all you need for this project. I’ve used 3 groups of colored LEDs to show the rise of the input voltage. Also 470 Ohm resistors are required to limit the LEDs current to acceptable levels. Schematic diagram is shown in the next figure.
In attached Python code you can see that Raspberry Pi I/O are grouped into 8 element list that allows to address them as a byte instead of individual bits. Input voltage range is divided into 8 segments with a defined LED pattern. A voltage is converted and normalized to fit one of these ranges. MAX 3.3v will turn all the LEDs ON. Adafruit-circuitpython-ads1x15 module should be installed in order for this design to work. LED bar graph operation is shown in a short video at the bottom of the page.
