New C18 3.0+ Compatible FRC Code

[Joe Ross]

Originally Posted by PhilBot

And finally I have

long Get_Gyro_Angle(void)
{
// Return the calculated gyro angle to the caller.
return(((gyro_angle * GYRO_SENSITIVITY * 5L) / (ADC_RANGE * ADC_UPDATE_RATE)) * GYRO_CAL_FACTOR);
}

So, since I've been caught before on this one.. I calculated the value of the divisor of this expression. ADC_RANGE * ADC_UPDATE_RATE = 2048 * 100 = 204800. So I'm dividing a "Long" by this number.... I should be able to calculate the maximum result I can get...

Max Long is 2147483648 so if I divide this by 204800 I get 10485 ... Which, in theory is the maximum result I can get...
But wait, this is millirads so the maximum angle I can measue is... just over 1.6 full rotations...

Oops... Either I did my math wrong, or I have to reduce my update rate.
In fact, this does reflect what I see in my log data... after getting to 10485 mRad, the angle starts counting down again...

So I need to reduce my ADC range/rate, or reduce my measurement accuracy (like changing to tenth of a degree.)

No wonder my bot corrected in the wrong direction on evey second lap

If you move the multiply by 5L to the end of the expression, it should give you 5 times longer before it roles over.