7.2.3 PID

Description

PID computes the controlOutput element of the data structure tPID:

controlOutput[n] = controlOutput[n-1] 
                    + controlHistory[n] * abcCoefficient[0] 
                    + controlHistory[n-1] * abcCoefficient[1] 
                    + controlHistory[n-2] * abcCoefficient[2] 
//where 
abcCoefficient[0] = Kp + Ki + Kd 
abcCoefficient[1] = -(Kp + 2*Kd) 
abcCoefficient[2] = Kd 
ControlHistory[n] =  MeasuredOutput[n] - ReferenceInput[n] 

Prototype

void PID ( tPID* PIDStruct );

Arguments

Returns

Pointer to PIDStruct

Remarks

controlOutput element is updated by the PID() routine. The controlOutput will be subject to saturation.

Source File

• pid_aa.s

Function Profile

System resource usage

• W0…W7 - used, not restored.
• ACCA, ACCB - used, not restored
• CORCON - saved, used, restored
• REPEAT - instruction usage – None