# IDE compiler error?
**URL:** https://community.simplefoc.com/t/ide-compiler-error/270
**Category:** Uncategorized
**Created:** [November 23, 2020, 1:38am UTC](https://community.simplefoc.com/t/ide-compiler-error/270 "2020-11-23T01:38:33Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Keshka](https://community.simplefoc.com/u/Keshka)
#### Post date: [November 23, 2020, 1:38am UTC](https://community.simplefoc.com/t/ide-compiler-error/270/1 "2020-11-23T01:38:33Z")
I have installed the library SimpleFOC version 2.0 Using Arduino IDE 1.8.13 Copied code from this page: [Reaction Wheel Pendulum | Arduino-FOC](https://docs.simplefoc.com/simplefoc_pendulum)
Compiler stops at: BLDCDriver3PWM motor = BLDCDriver3PWM(9, 10, 11, 8);
with this error:
Arduino: 1.8.13 (Windows 10), Board: “Arduino Mega or Mega 2560, ATmega2560 (Mega 2560)”
FOC\_code\_for\_inverted\_pend:10:16: error: conflicting declaration ‘BLDCDriver3PWM motor’
BLDCDriver3PWM motor = BLDCDriver3PWM(9, 10, 11, 8);
```
^ ~~~~
```
G:\Keshka\Documents\Arduino\FOC\_code\_for\_inverted\_pend\FOC\_code\_for\_inverted\_pend.ino:8:11: note: previous declaration as ‘BLDCMotor motor’
BLDCMotor motor = BLDCMotor(11);
```
^ ~~~~
```
G:\Keshka\Documents\Arduino\FOC\_code\_for\_inverted\_pend\FOC\_code\_for\_inverted\_pend.ino: In function ‘void setup()’:
FOC\_code\_for\_inverted\_pend:34:3: error: ‘driver’ was not declared in this scope
driver.voltage\_power\_supply = 12;
^ ~~~~~
G:\Keshka\Documents\Arduino\FOC\_code\_for\_inverted\_pend\FOC\_code\_for\_inverted\_pend.ino:34:3: note: suggested alternative: ‘div’
driver.voltage\_power\_supply = 12;
^ ~~~~~
div
G:\Keshka\Documents\Arduino\FOC\_code\_for\_inverted\_pend\FOC\_code\_for\_inverted\_pend.ino: In function ‘void loop()’:
FOC\_code\_for\_inverted\_pend:74:25: error: ‘sign’ was not declared in this scope
```
target_voltage = -sign(pendulum.getVelocity())*driver.voltage_power_supply*0.4;
^~~~
```
G:\Keshka\Documents\Arduino\FOC\_code\_for\_inverted\_pend\FOC\_code\_for\_inverted\_pend.ino:74:25: note: suggested alternative: ‘sin’
```
target_voltage = -sign(pendulum.getVelocity())*driver.voltage_power_supply*0.4;
^~~~
sin
```
FOC\_code\_for\_inverted\_pend:74:54: error: ‘driver’ was not declared in this scope
```
target_voltage = -sign(pendulum.getVelocity())*driver.voltage_power_supply*0.4;
^ ~~~~~
```
G:\Keshka\Documents\Arduino\FOC\_code\_for\_inverted\_pend\FOC\_code\_for\_inverted\_pend.ino:74:54: note: suggested alternative: ‘div’
```
target_voltage = -sign(pendulum.getVelocity())*driver.voltage_power_supply*0.4;
^ ~~~~~
div
```
G:\Keshka\Documents\Arduino\FOC\_code\_for\_inverted\_pend\FOC\_code\_for\_inverted\_pend.ino: In function ‘float controllerLQR(float, float, float)’:
FOC\_code\_for\_inverted\_pend:105:15: error: ‘driver’ was not declared in this scope
if(abs(u) \> driver.voltage\_power\_supply\*0.7) u = sign(u)_driver.voltage\_power\_supply_0.7;
```
^ ~~~~~
```
G:\Keshka\Documents\Arduino\FOC\_code\_for\_inverted\_pend\FOC\_code\_for\_inverted\_pend.ino:105:15: note: suggested alternative: ‘div’
if(abs(u) \> driver.voltage\_power\_supply\*0.7) u = sign(u)_driver.voltage\_power\_supply_0.7;
```
^ ~~~~~
div
```
FOC\_code\_for\_inverted\_pend:105:52: error: ‘sign’ was not declared in this scope
if(abs(u) \> driver.voltage\_power\_supply\*0.7) u = sign(u)_driver.voltage\_power\_supply_0.7;
```
^~~~
```
G:\Keshka\Documents\Arduino\FOC\_code\_for\_inverted\_pend\FOC\_code\_for\_inverted\_pend.ino:105:52: note: suggested alternative: ‘sin’
if(abs(u) \> driver.voltage\_power\_supply\*0.7) u = sign(u)_driver.voltage\_power\_supply_0.7;
```
^~~~
sin
```
exit status 1
conflicting declaration ‘BLDCDriver3PWM motor’
This report would have more information with
“Show verbose output during compilation”
option enabled in File → Preferences.
PS. I can not go to my profile page to add my photo. Get 404 not found error
---
### Author:  [@Keshka](https://community.simplefoc.com/u/Keshka)
#### Post date: [November 23, 2020, 4:24am UTC](https://community.simplefoc.com/t/ide-compiler-error/270/2 "2020-11-23T04:24:18Z")
Looking at code differences from [Position Control example | Arduino-FOC](https://docs.simplefoc.com/position_control_example)
and [Reaction Wheel Pendulum | Arduino-FOC](https://docs.simplefoc.com/simplefoc_pendulum)
this line in pendulum
`BLDCDriver3PWM motor = BLDCDriver3PWM(9, 10, 11, 8);`
is this in position control
`BLDCDriver3PWM driver = BLDCDriver3PWM(9, 10, 11, 8);`
using the line from position control instead of said line from pendulum and it compiles fine now
Keshka
---
### Author:  [@Antun\_Skuric](https://community.simplefoc.com/u/Antun_Skuric)
#### Post date: [November 23, 2020, 6:51am UTC](https://community.simplefoc.com/t/ide-compiler-error/270/3 "2020-11-23T06:51:25Z")
Thanks a lot for the heads up, I just did a lot of refactoring in the docs and unfortunately this is to be expected 😃
I am not the best typer 😃
I will update the docs right away!