How to code a servomotor with two buttons in arduino? - arduino-uno

Question

I wanted to make a servomotor oscilate between 0-90 degrees when i push a button, but when i push another one, it stops oscillating and then remains in its latest position.
i started with this:
#include <Servo.h>
Servo myservo;
int pos = 0;
const int button1 = 5;
const int button2 = 6;
int lastpos = pos;
void setup() {
myservo.attach(3);
pinMode(button1, INPUT);
pinMode(button2, INPUT);
}
void loop() {
if(digitalRead(button1) == HIGH)
{for(pos = 0; pos <= 90; pos += 1)
{myservo.write(pos);
for(pos = 90; pos >= 0; pos -= 1)
{myservo.write(pos);
delay(36);
} } if(digitalRead(button2) == HIGH){ myservo.write(lastpos);}}}

Answer 1

To start, take a look at how to format code inside a question. It makes it a lot easier to read and help you out. See below for how I formatted for the site, but also readability.
Servo myservo;
int pos = 0;
const int button1 = 5;
const int button2 = 6;
int lastpos = pos;
void setup() {
myservo.attach(3);
pinMode(button1, INPUT);
pinMode(button2, INPUT);
}
void loop() {
if(digitalRead(button1) == HIGH) {
for(pos = 0; pos <= 90; pos += 1) {
myservo.write(pos);
for(pos = 90; pos >= 0; pos -= 1) {
myservo.write(pos);
delay(36);
}
}
if(digitalRead(button2) == HIGH) {
myservo.write(lastpos);
}
}
}
There are several issues with your code based on your description of what you are trying to achieve. First, let's start with the button presses. You are ready the button state, but your code will only detect the button if it is pressed at the exact moment you are doing the digital read. Here's a good resource for reading up on how to properly implement buttons on Arduino: https://www.logiqbit.com/perfect-arduino-button-presses
The second objective is to have the servo sweep back and forth, but stop when you press a button. Your for loops won't let that happen. As currently written, you will always do a sweep to one end and back and then check the next button.
You should update the position of the servo once each time through the loop so you can check on the status of the buttons. In pseudo-code, what I suggest you do is:
void loop() {
//Check button statuses
if(button1), start sweep
if(button2), stop sweep
//Update sweep position
if(ascending && pos < 90) {
//You should be increasing in angle and you haven't reached 90 yet
ascending = TRUE;
pos += 1
myservo.write(pos);
delay(36); //Or whatever delay you need for the servo
} else if(pos > 0) {
//You already reached 90 and are coming back down to 0
ascending = FALSE;
pos -= 1;
delay(36);
}