A pH meter? is an instrument used to measure the acidity or alkalinity of a solution - also known as pH. The code consists of taking 10 samples of the analogue input A0, ordering them and discarding the highest and the lowest and calculating the mean with the six remaining samples by converting this value to voltage in the variable pHVol, then using the equation that we have calculated with the pH reference values we convert pHVol to pHValue and send it to the serial port and LCD display