unexpected primary-expression before ';' token

Question

I'm new to the Arduino world and am working on a sketch to run a servo up and down with a spdt switch. My code is :

include #include<Servo.h>
int pos = 0;

Servo myservo;
void setup() {
  pinMode(2, INPUT);
  pinMode(3, INPUT);
  myservo.attach(9);
}
void loop() {
  if (digitalRead(2) == HIGH && pos < 180) {
    pos++;
    servo.write(pos);
    delay(15);
  }
  if (digitalRead(3) == HIGH && pos > 0) {
    pos--;
    servo.write(pos);
    delay(15);
  }
}

When I compile I get the "unexpected primary-expression before ';' token" error with exit status 1.

What am I doing wrong???

Use myservo instead of servo in the blocks (to start with :). — Mikael Patel
– Mikael Patel, Commented May 10, 2017 at 22:41
You are looking at the last compiler error, but the first one is the most important. You can scroll up in that output window to find the first compiler error. Are you using Arduino IDE 1.8.2 with an Arduino Uno ? because I get a different compiler error. — Jot
– Jot, Commented May 10, 2017 at 23:12

L. Paw · Accepted Answer · 2017-05-12 00:17:47Z

4

1) You should be using:

myservo.write(pos);

instead of

servo.write(pos);

for all of your methods.

2) Change:

include #include<Servo.h>

to

#include <Servo.h>

This code only verifies when it is run on certain boards*, so make sure you are using one of those boards.Good luck and welcome to the Arduino world!:)

*Verify that your board will work, I know Mega, Uno and Nano will function properly.

P.s. Here is the whole code in correct format:

#include <Servo.h>

int pos = 0;

Servo myservo;
void setup() {
 pinMode(2, INPUT);
 pinMode(3, INPUT);
 myservo.attach(9);
}
void loop() 
{
  if ( (digitalRead(2) == HIGH) && (pos < 180)) {
    pos++;
    myservo.write(pos);
    delay(15);
  }
  if ( (digitalRead(3) == HIGH) && (pos > 0)) {
    pos--;
    myservo.write(pos);
    delay(15);
  }
}

edited May 12, 2017 at 0:17

answered May 10, 2017 at 23:29

L. Paw

1311 silver badge5 bronze badges

I got it working on a NANO without the stacked parenthesis. My problem was I was trying to use an external servo library (not needed) and my USB cable was no good (power only)

C Snyder
– C Snyder

2017-05-12 00:07:31 +00:00
Commented May 12, 2017 at 0:07
@CSnyder okay! Glad to hear it ran on Nano, I will correct my answer, and overall that you got your project working. Good luck!

L. Paw
– L. Paw

2017-05-12 00:16:33 +00:00
Commented May 12, 2017 at 0:16

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