CedarGroveStudios / CircuitPython_RangeSlicer

A CircuitPython class for scaling a range of input values into indexed/quantized output values. Adjustable output slice hysteresis for noise reduction.

Introduction

RangeSlicer is a general-purpose CircuitPython analog value converter that linearly scales the input then quantizes it into a collection of precise output slice values. The class detects input value changes and applies selectable hysteresis when slice edge thresholds are reached to eliminate dead-zone noise issues without filtering delays. Applications include converting rotary knob position to discrete ranges of MIDI values, analog signal noise processing, level detection, rotary switch emulation, and signal display.

The effect of using hysteresis to clean up a noisy signal:

Dependencies

This driver depends on:

• Adafruit CircuitPython

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle or individual libraries can be installed using circup.

Installing to a Connected CircuitPython Device with Circup

Make sure that you have circup installed in your Python environment. Install it with the following command if necessary:

pip3 install circup

With circup installed and your CircuitPython device connected use the following command to install:

circup install cedargrove_rangeslicer

Or the following command to update an existing version:

circup update

Usage Example

"""Reads two potentiometer inputs and produces -1.0 to +1.0 normalized outputs,
one with an inverted output range."""

import time
import board
from analogio import AnalogIn
import cedargrove_rangeslicer as rs

print("Two Normalized Outputs: RangeSlicer example 01")

"""Establish range_slicer instances, one for each analog potentiometer
input. Input ranges are adjusted for unique potentiometer inaccuracies and
noise. Slice size divides the output into 10 slices. Hysteresis factor is
25% of a slice."""

ctrl_0 = rs.Slicer(200, 65335, -1.0, +1.0, 0.2, 0.25)
ctrl_1 = rs.Slicer(375, 65520, +1.0, -1.0, 0.2, 0.25)

# establish analog inputs
pot_0 = AnalogIn(board.A0)
pot_1 = AnalogIn(board.A1)

while True:  # read potentiometer values
    control_0 = pot_0.value
    control_1 = pot_1.value

    # calculate output values and print (or plot in Mu)
    out_0 = ctrl_0.range_slicer(control_0)
    out_1 = ctrl_1.range_slicer(control_1)
    print( (control_0 / 65535, control_1 / 65535, out_0, out_1) )

    time.sleep(0.1)  # pause for 0.1 second

Documentation

RangeSlicer CircuitPython Driver API Class Description

Contributing

Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.