Penggunaan rotary encoder di sistem Arduino

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A rotary encoder, also called a shaft encoder, is an electro-mechanical device that converts the angular position or motion of a shaft or axle to an analog or digital signal.

There are two main types: absolute and incremental (relative). The output of absolute encoders indicates the current position of the shaft, making them angle transducers. The output of incremental encoders provides information about the motion of the shaft, which is typically further processed elsewhere into information such as speed, distance and position.

Rotary encoders are used in many applications that require precise shaft unlimited rotation—including industrial controls, robotics, special purpose photographic lenses, computer input devices (such as optomechanical mice and trackballs), controlled stress rheometers, and rotating radar platforms.

~https://en.wikipedia.org/wiki/Rotary_encoder

A rotary encoder is a type of position sensor which is used for determining the angular position of a rotating shaft. It generates an electrical signal, either analog or digital, according to the rotational movement.

Gambar 1.

Gambar 2.

This rotary encoder is also known as quadrature encoder or relative rotary encoder and its output is a series of square wave pulses.

How Rotary Encoder Works  [click to read more]

~howtomechatronics.com

Incremental Encoder Quadrature Output Waveform

An incremental rotary encoder generates two output signals while its shaft is rotating which is also called quadrature ouptut. Depending on the direction, one of the signals leads the other. You can see the output signal waveforms of an incremental rotary encoder and the expected bit sequence below.

Gambar 3.

As you can see from the figure, both of the outputs stays HIGH at the initial state. When the encoder shaft starts to rotate in clockwise direction, Output A falls to LOW first and Output B follows it with a lag. In a counter-clockwise direction the operation turns opposite. Time intervals on the waveform depend on the rotation speed but the signal lagging is guaranteed in encoder operation. We will build the whole scenario on this characteristic of the incremental rotary encoder.

~How to Use a Rotary Encoder in an MCU-Based Project

Mengenal Keyes KY-04 dan mencoba kode program sederhana.

Contoh kode dari:

http://henrysbench.capnfatz.com

Contoh kode dari:

http://howtomechatronics.com/tutorials/arduino/rotary-encoder-works-use-arduino/

Description of the code: So first we need to define the pins to which our encoder is connected and define some variables needed for the program. In the setup section we need to define the two pins as inputs, start the serial communication for printing the results on the serial monitor, as well as read the initial value of the output A and put the value into the variable aLastState.

Then in the loop section we read the output A again but now we put the value into the aState variable. So if we rotate the encoder and a pulse is generated, these two values will differ and the first “if” statement will become true. Right after that using the second “if” statement we determine the rotation direction. If the output B state differ from the output A state the counter will be increased by one, else it will be decreased. At the end, after printing the results on the serial monitor, we need to update the aLastState variable with aState variable.

That’s all we need for this example. If upload the code, start the Serial Monitor and start rotating the encoder we will start getting the values in the serial monitor. The particular module that I have makes 30 counts each full cycle.

Gambar 20.

Berikut contoh-contoh kode program, silakan membaca situs sumber aslinya untuk lebih memahami. Beberpa kode memerlukan pustaka/library yang dapat dicari melalui halaman sumber kode.

Contoh kode program dari https://github.com/PaulStoffregen/Encoder (Basic.pde)

Contoh kode program dari https://github.com/PaulStoffregen/Encoder (NoInterrupts.pde)

Contoh kode program dari https://github.com/mathertel/RotaryEncoder (InterruptRotator.ino)

 

 

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