Why can't X be used as a function? - arduino

Question

Sorry for the messy codebase. I am new to C++.
I'm trying to tie a loop and function together. (1) A moisture sensor and (2) a servo to turn a lever on and off based on moisture.
I'm receiving an error that 'servo' cannot be used as a function. I've tried changing servo to some other name. I'm not using servo anywhere else, such as a variable, so that doesn't seem like the issue.
Does anyone have any other advice?
#include "Servo.h"
Servo myservo; // create servo object to control a servo
int pos = 0; // servo position variable
#define SensorPin A0
float sensorValue = 0;
bool lever = 0; // soil moisture sensor variable; 0 = dry; 1 = wet;
bool pump = 0; // pump is set to 0, which = off
// servo function
void servo(bool);
void setup() {
Serial.begin(9600); // soil moisture sensor setup
myservo.attach(9); // servo setup
}
// soil moisture sensor loop
void loop() {
for (int i = 0; i <= 100; i++) {
sensorValue = sensorValue + analogRead(SensorPin);
delay(20);
}
sensorValue = sensorValue/100.0;
Serial.print("Moisture level: ");
Serial.print(sensorValue);
Serial.print(";");
if(sensorValue > 1000) {
lever = 0; // dry
}
if(sensorValue < 1000) {
lever = 1; // wet
}
switchOnOff(lever);
delay(1000);
}
// define the servo function
void switchOnOff(bool lever) {
Serial.print(" Lever: ");
Serial.print(lever);
Serial.print(";");
Serial.print(" Pump: ");
Serial.print(pump);
Serial.println(";");
if(lever == 0 && pump == 0) { // it is dry and pump is off, pump needs to be turned on
for (pos = 90; pos <= 180; pos++) { // goes from 0 degrees to 90 degrees
// in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15);
}
delay(4000);
for (pos = 180; pos >= 90; pos--) { // goes from 90 degrees to 0 degrees
// in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15);
}
pump = 1; // noting that pump is on
}
if(lever == 0 && pump == 1) { // it is dry and pump is on
return; // do nothing, return
}
if(lever == 1 && pump == 1) { // it is wet and pump is on, pump needs to be turned off
for (pos = 90; pos <= 180; pos++) { // goes from 90 degrees to 0 degrees
// in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15);
}
delay(4000);
for (pos = 180; pos >= 90; pos--) { // goes from 0 degrees to 90 degrees
// in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15);
}
pump = 0; // noting that pump is off
}
if(lever == 1 && pump == 0) { // it is wet and pump is off
return; // do nothing, return
}
}
Thank you.

Answer 1

The problem is in that you try to use the servo() function before properly declaring it. First, you need to declare a function before it can be mentioned in your code. Second, your definition for the servo() is incorrect. The int servo(lever), where lever is not a type. You should look toward the following: int servo(bool lever);, where lever is a parameter of type bool which the servo() function takes.
Then, your function does not return anything, it only has some "side-effects" such as myservo.write(pos);. So, it should be void.
Try the following arrangement:
#include "Servo.h"
Servo myservo; // create servo object to control a servo
// twelve servo objects can be created on most boards
// Declare the function
void servo(bool);
int pos = 0; // variable to store the servo position
#define SensorPin A0
float sensorValue = 0;
bool lever = 0; // lever is global variable of type bool
void setup() {
myservo.attach(9); // attaches the servo on pin 9 to the servo object
Serial.begin(9600);
}
void loop() {
for (int i = 0; i <= 100; i++) {
sensorValue = sensorValue + analogRead(SensorPin);
delay(1);
}
sensorValue = sensorValue/100.0;
Serial.println(sensorValue);
delay(30);
if(analogRead(0 > 100)) {
lever = 1;
}
if(analogRead(0 < 100)) {
lever = 0;
}
servo(lever);
}
// Define the function
void servo(bool lever) {
if(lever == 1) { // On
for (pos = 0; pos <= 180; pos += 1) { // goes from 0 degrees to 180 degrees
// in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
}
}
if(lever == 0) { // Off
for (pos = 180; pos >= 0; pos -= 1) { // goes from 180 degrees to 0 degrees
myservo.write(pos); // tell servo to go to position in variable 'pos'
}
}
}
P.S. There was also a mess with setup() being redefined here and there.