Example 01: Analog signal readings
This is a walkthrough of an example supplied with the KeyDetector library that demonstrates use of a library to get analog signal readings.
In this example we will create sort of absolute rotary encoder using potentiometer and KeyDetector library. Rotation of the knob results in printing its current position and direction of rotation. The whole range of rotation is divided into several segments with the middle points at 25%, 50%, 75% and 100% of the range. Hence the segments: [12.5% .. 37.5%], [37.5% .. 62.5%], [62.5% .. 87.5%], [87.5% .. 100%]. Once the bounds of segments are crossed the output is printed.
ADC (analog-to-digital converter) used in Arduino UNO has resolution of 10-bit, so aforementioned ranges correspond to the following levels of signal read from analog input: [127 .. 383], [383 .. 639], [639 .. 895], [895 .. 1023] (with middle points at 255, 511, 767 and 1023).
We will use KeyDetector to listen for the signal to fall into one of these ranges and then determine the direction of rotation by comparing current range with the previously detected one.
- Arduino UNO or compatible
- 10kOhm potentiometer
- 1MOhm resistor (optional)
- 100nF capacitor (optional)
Schematic for this example is very simple. Resistor R2 and capacitor C1 form optional low-pass RC-filter. It helps to smoothen any transient processes or ripple that may occur during pot rotation. You may opt not to implement one (or implement version with another R, C values - I just used ones that happened to be in possession at the time).
Commented sketch is supplied with the library and can be found at "examples/Example-01_Analog/Example-01_Analog.ino".