adjusting value range

Projects General Guidance
1

Hey guys, I am trying to get the angles from the mpu6050.

Progress: I got the angles from the mpu6050 from 0-360 deg.
To Solve: I want to convert these to -180 to 180 deg.
Problem: The methdod i am using has some problem.
the output has a huge spike when the angle shanges from negative to positive.
This is the code i used:

if (x >= 180) {
    x = x - 360;
  }
  else if(a<180){
    x = x;
  }
Serail.println(x);
2

Given 0 <= X < 360

-180 <= ( X - 180 ) < 180

You do know that it's 0 to 359 since 0 and 360 are the exact same direction?

-180 == +180

3

Yhea i know that.

BTW here is a screenshot of what i got(attached).

arduino.png

4

This is the code i used:

Nope.
Because that code didn't compile.

What is so hard about cut-and-paste?

5

PROBOT135:
Yhea i know that.

BTW here is a screenshot of what i got(attached).

So subtract 180 from your X = 0 to 359 and X is within -180 to 179.

To go from -180 to 179 to 0 to 359 just add 180. No need to test if X is negative or positive, just add 180.

6

GoForSmoke:
So subtract 180 from your X = 0 to 359 and X is within -180 to 179.

To go from -180 to 179 to 0 to 359 just add 180. No need to test if X is negative or positive, just add 180.

You can not just subtract 180. If X is a direction, X-180 is in the oppsosite direction...

To "convert" from 0 - 359 to -180 - 179 you have to subtract 360 from X if (X>=180).

if (x >= 180) {
    x = x - 360;
  }

PROBOT135:
Problem: The methdod i am using has some problem.
the output has a huge spike when the angle shanges from negative to positive.

This is not a problem related to the -180/180 vs 0/360 representation of a changing angle.
You will see the same "spike" when going from 359 to 0 degrees.
To handle the transition, you might have to account for the direction of change.

7

leongjerland:
You can not just subtract 180. If X is a direction, X-180 is in the oppsosite direction...

To "convert" from 0 - 359 to -180 - 179 you have to subtract 360 from X if (X>=180).

if (x >= 180) {

x = x - 360;
  }





This is not a problem related to the -180/180 vs 0/360 representation of a changing angle.
You will see the same "spike" when going from 359 to 0 degrees.
To handle the transition, you might have to account for the direction of change.

You're right.