Filter

The ADC may perform inaccurate measurements due to noise in the system, which may distort the real value. Applying filters can reduce the noise and improve the accuracy of the measurements. The FilterAvg class from Listing provides a simple average filter for ADC samples.

It requires the instance of the ADC class and the number of samples to average. In the calc() method, the sum of the samples in a buffer buf is added up and divided by the number of samples at the end. This calculates the average value and returns it as a filtered value.Ṫhis class is needed to minimize the noise of the raw data and provide a more accurate measurement.

Listing software filter

class FilterAvg():
    '''Average filter for adc samples'''
    def __init__(self, adc: ADC, samples: int):
        self.buf = 0.
        self.samples = samples
        self.adc = adc

    def calc(self):
        for sample in range(self.samples):
            self.buf += self.adc.read_u16()
        filtered = self.buf/self.samples
        self.buf = 0.
        return(filtered)