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Related or required files and link to this lesson
In this lesson we learn how to use a rotary encoder knob. Then we learn how to use it to control position of
a servo motor (97-2) . In this lesson (97-3) we also display the position of servo motor on LCD screen using Arduino. This code will work with all Arduino board.
This code demonstrating rotary encoder and displayes the angel on LCD1602 or LCD2004 screen. When pressing the
rotary encoder push button, it returns the servo to the home position. See video for demonstraiton.
/*
* Lesson 97-3: Controlling Servo Motor using Rotary Encoder and Display Angel On LCD
* Watch full details video: https://youtu.be/6xVLbNlmK-g
This video is part of Arduino Step by Step Course which starts here: https://youtu.be/-6qSrDUA5a8
If you found this tutorial helpful, please support me so I can continue creating
content like this. Make a donation using PayPal by credit card https://bit.ly/donate-robojax
* This code is "AS IS" without warranty or liability. Free to be used as long as you keep this note intact.*
* This code has been download from Robojax.com
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
* Updated by Ahamd Shamshiri on Jan 23, 2022
* Encoder Library - Basic Example
* http://www.pjrc.com/teensy/td_libs_Encoder.html
*
* This example code is in the public domain.
*/
const int SW_PIN = 4;//define a pin for rotary encode switch
const int PIN_A =2;
const int PIN_B =3;
#include <Encoder.h>
// Change these two numbers to the pins connected to your encoder.
// Best Performance: both pins have interrupt capability
// Good Performance: only the first pin has interrupt capability
// Low Performance: neither pin has interrupt capability
Encoder myEnc(PIN_A, PIN_B);
// avoid using pins with LEDs attached
const int homePosition = 90; //initial position
const int stepValue = 3;//how fast the servo should rotate when turning the knob
const int servoPin = 9;//~must be a pin that that is labeled with ~
#include <Servo.h>
Servo myservo; // create servo object to control a servo
int servoAngel =homePosition;
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
// Set the LCD address to 0x27 or 0x3F for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x3F, 16, 2);
void setup() {
Serial.begin(9600);
pinMode(SW_PIN, INPUT);
Serial.println("Robojax Encoder with LCD and Servo");
myservo.attach(servoPin); // attaches the servo on pin
myservo.write(servoAngel);//move servo to initial position
lcd.begin();
// Turn on the blacklight and print a message.
lcd.backlight();
lcd.print("Robojax Encoder");
lcd.setCursor (0,1); // go to start of 2nd line
lcd.print("Servo Test");
delay(2000);
lcd.clear();// clear previous values from screen
lcd.print("Robojax Encoder");
lcd.setCursor (0,1); // go to start of 2nd line
lcd.print("Angel: ");
}
long oldPosition = -999;
void loop() {
long newPosition = myEnc.read();
if (newPosition != oldPosition) {
if(newPosition > oldPosition)
{
int newStep = abs(newPosition - oldPosition);
Serial.print("Angle ");
Serial.println(servoAngel);
servoAngel -= stepValue;
if(servoAngel <0)
servoAngel =0;
myservo.write(servoAngel); //move servo to new angel
lcdAngel(servoAngel);//print on LCD
}
if(newPosition < oldPosition )
{
int newStep = abs(newPosition - oldPosition);
Serial.print("Angle ");
Serial.println(servoAngel);
servoAngel += stepValue;
if(servoAngel >180)
servoAngel =180;
myservo.write(servoAngel); //move servo to new angel
lcdAngel(servoAngel);//print on LCD
}
oldPosition = newPosition;//remember the new position
}
if( digitalRead(SW_PIN) == LOW)
{
Serial.print("Home: ");
Serial.println(homePosition);
servoAngel =homePosition;
myservo.write(servoAngel); //move servo to new angel
lcdAngel(servoAngel);//print on LCD
}
//delay(200);
}
/*
* lcdAngel(int angel)
* prints the angle on LCD
* written by Ahmad Shamshiri
* www.robojax.com
* Jan 27, 2022 at 13:18
* Watch full details video: https://youtu.be/6xVLbNlmK-g
*/
void lcdAngel(int angel)
{
int startChar =7;
for(int i=startChar; i<16; i++)
{
lcd.setCursor (i,1);
lcd.print(" ");
}
lcd.setCursor (startChar,1); // line 1
lcd.print(angel);
lcd.print((char)223);
}
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