'Servo_Pointer' was not declared in this scope

Question

I can't seem to find the error I made; can anyone help me?

The error message: 'Servo_Pointer' was not declared in this scope

I get the error at the end of the code with the line: Servo_Pointer.write(servo_pos)

The code:

const int photo_left = A0; // select the input pins for the photoresistor
const int photo_right = A1; 
const int ledPin_1 = 2; // These leds will be used for the testing of the pointing of the servo motor
const int ledPin_2 = 4;
const int ledPin_3 = 7;
const int ledPin_4 = 8;
const int ledPin_5 = 12;
const int photoValue = 0; // variable to store the value coming from the photoresistor
const int numReadings = 10;
int readings[numReadings]; // the readings from the analog input
int readIndex = 0; // the index of the current reading
int total = 0; // the running total
int average = 0; // the average
void setup() {
 // declare the ledPin as an OUTPUT:
 pinMode(ledPin_1, OUTPUT);
 pinMode(ledPin_2, OUTPUT);
 pinMode(ledPin_3, OUTPUT);
 pinMode(ledPin_4, OUTPUT);
 pinMode(ledPin_5, OUTPUT);
 Serial.begin(9600);
 #include <Servo.h>
 Servo Servo_Pointer;
 Servo_Pointer.attach(9);
 int servo_pos = 0;
 // initialize serial communication with computer:
 Serial.begin(9600);
 // initialize all the readings to 0:
 for (int thisReading = 0; thisReading < numReadings; thisReading ) {
 readings[thisReading] = 0;
 }
}
void loop() {
 Servo_Pointer.write(servo_pos); // tell servomotor to go to position in variable 'servo_pos'
 delay(15); // waits 15ms for the servo to reach the position
 // turn the ledPin on
 delay(15);
}

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Answer 1

You should make Servo Servo_Pointer; global, i.e. place it outside the setupfunction, e.g. after the line int average = 0;.

In your code, it is a local variable within the setup function. When this function ends, the local variables within this function (such as Servo_Pointer ) do not exist anymore.

By making the variable global, you can use it anywhere. However, it's not a good coding practice to use global variables when not needed.

A benefit of making the variable global is that you can see the memory consumption of the instance of Servo_Pointer when compiling.

Also see the comment of timemage below: Don't put #include statements in the middle of your code, put them in the beginning of your code.

• timemage: Might be worth adding that it's at least unconventional to have an #include directive in the middle of your function.
• Michel Keijzers: @timemage Good catch, I did a search on Servo_Pointer missing that line.

Answer 2

You need to place the decleration outside of your setup() function. In other words, you need to move the following 3 lines and place then above your setup() function:

#include <Servo.h>
Servo Servo_Pointer;
int servo_pos = 0;

Your code should look like this:

#include <Servo.h>
const int photo_left = A0; // select the input pins for the photoresistor
const int photo_right = A1; 
const int ledPin_1 = 2; // These leds will be used for the testing of the pointing of the servo motor
const int ledPin_2 = 4;
const int ledPin_3 = 7;
const int ledPin_4 = 8;
const int ledPin_5 = 12;
const int photoValue = 0; // variable to store the value coming from the photoresistor
const int numReadings = 10;
int readings[numReadings]; // the readings from the analog input
int readIndex = 0; // the index of the current reading
int total = 0; // the running total
int average = 0; // the average
int servo_pos = 0;
Servo Servo_Pointer;
void setup() {
 // declare the ledPin as an OUTPUT:
 pinMode(ledPin_1, OUTPUT);
 pinMode(ledPin_2, OUTPUT);
 pinMode(ledPin_3, OUTPUT);
 pinMode(ledPin_4, OUTPUT);
 pinMode(ledPin_5, OUTPUT);
 Serial.begin(9600);
 Servo_Pointer.attach(9);
 // initialize serial communication with computer:
 Serial.begin(9600);
 // initialize all the readings to 0:
 for (int thisReading = 0; thisReading < numReadings; thisReading ) {
 readings[thisReading] = 0;
 }
}
void loop() {
 Servo_Pointer.write(servo_pos); // tell servomotor to go to position in variable 'servo_pos'
 delay(15); // waits 15ms for the servo to reach the position
 // turn the ledPin on
 delay(15);
}