Using one button to start the Servo motor and another to stop

Other Hardware Motors, Mechanics, Power and CNC
1

I've been having trouble with a current project of mine where I need to make a servo rotate in a range of 60-120 degrees at a speed of 11 cycles per minute. I want one button that gets the servo rotating continuously and the other button to stop the rotation. With my current code it only swings for one cycle and the stop button won't interrupt it until the end. I tried to use a while loop to get the servo to continuously rotate but then the stop button won't work at all. Can someone help me?

Here's the code:

#include <Servo.h>

Servo myservo; // create servo object to control a servo
// twelve servo objects can be created on most boards

int pos = 0; // variable to store the servo position

const int start_button = 2; //start button
const int stop_button = 7; //stop button

int startbuttonState = 0;
int stopbuttonState = 0;

const int greenLED = 10;
const int redLED = 11;

void setup() {
myservo.attach(9); // attaches the servo on pin 9 to the servo object

pinMode(start_button, INPUT);
pinMode(stop_button, INPUT);

pinMode(redLED, OUTPUT);
pinMode(greenLED, OUTPUT);
}

void loop() {

startbuttonState = digitalRead(start_button);
stopbuttonState = digitalRead(stop_button);

if (startbuttonState == HIGH) {

digitalWrite(greenLED, HIGH);
digitalWrite(redLED, LOW);
for (pos = 55; pos <= 115; pos += 1) { // goes from 55 degrees to 115 degrees
// in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(45); // waits 15ms for the servo to reach the position
}
for (pos = 115; pos >= 55; pos -= 1) { // goes from 115 degrees to 55 degrees
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(45); // waits 15ms for the servo to reach the position
}
}
else if (stopbuttonState == HIGH) {
digitalWrite(greenLED, LOW);
digitalWrite(redLED, HIGH);
myservo.write(90);
}
}

2

The problem is once the condition of the “start button “ being high has been met , the program then loops until it reaches the end of the servo movement in your “for “ loop , and won’t see the “else” statement until next time around the loop , by which time the servo has completed its moves . You need to change that so that within the loop you check the state of the stop switch at each step .

There are lots of ways to do this , you could have an “if” the stop button is low move the servo a bit , then repeat .

It’s useful to put print statements into your sketch so it’s easier to tell if the sketch is doing what you think , then take them out of the finished version when it’s all working

3

Have a look at how the code is organized in Several Things at a Time. The code includes a servo sweep and a button that operates an LED even while the servo is moving.

Note how each function runs very briefly and returns to loop() so the next one can be called. None of the functions tries to complete a task in one call. And there may be dozens of calls to a function before it is actually time for it to do anything.

...R