Arduino Digital Low-Pass Filter 2.0

Improving Current Sensor Readings with Digital Filtering

Introduction to the Project

• The speaker introduces a new project involving an ACS 712 current sensor, noting that the output is noisy and unreliable due to noise levels around 100 milliamps.

• The speaker considers using a digital filter to improve the sensor's readings, referencing a previous video on low-pass filtering techniques implemented in Python and Arduino.

Implementing Low-Pass Filtering

• The speaker presents the difference equations for a first-order low-pass filter and shares code for reading from the ACS 712 sensor, which involves rescaling voltage to current based on specifications.

• Variables are introduced to store historical data of raw and filtered signals (XNUS1 and YNUS1), essential for applying the difference equation in filtering.

Enhancements in Filtering Technique

• After initial filtering, the speaker contemplates further improvements by simplifying coefficient derivation; previously done in Python, now integrated directly into Arduino code.

• A new version of the digital low-pass filter (Arduino digital low-pass filter 2.0) is introduced, allowing users to adjust cutoff frequency without needing external software like Python.

Using the New Filter Class

• Instructions are provided on how to implement this new filter class within Arduino code: copy it at the top of your script and create instances for each signal requiring filtering.

• Four parameters are necessary: filter order (first or second), cutoff frequency in Hertz, sampling frequency (estimated as 1 kHz), and a boolean flag for automatic sampling frequency computation based on loop function duration.

Results of Filter Application