2004 Microchip Technology Inc.
DS00908A-page 41
AN908
InvPark.s
;*******************************************************************
; InvPark
;
;Description:
;
Calculate the inverse Park transform. Assumes the Cos and Sin values
;
are in the ParkParm structure.
;
Valpha = Vd*cos(Angle) - Vq*sin(Angle)
;
Vbeta = Vd*sin(Angle) + Vq*cos(Angle)
;
This routine works the same for both integer scaling and 1.15 scaling.
;
;Functional prototype:
;
void InvPark( void )
;On Entry:
The ParkParm structure must contain qCos, qSin, qVd and qVq.
;On Exit:
ParkParm will contain qValpha, qVbeta.
;
;Parameters:
;
Input arguments:
None
;
Return:
Void
;
SFR Settings required:
CORCON.SATA = 0
;
Support routines required:
None
;
Local Stack usage:
None
;
Registers modified:
w3 -> w7, A
;
Timing:
About 14 instruction cycles
;*******************************************************************
;
include "general.inc"
;
External references
include "park.inc"
;
Register usage
.equ ParmW,
w3
; Ptr to ParkParm structure
.equ SinW,
w4
.equ CosW,
w5
.equ VdW,
w6
; copy of qVd
.equ VqW,
w7
; copy of qVq
;=================== CODE =====================
.section
.text
.global
_InvPark
.global
InvPark
_InvPark:
InvPark:
;; Get qVd, qVq from ParkParm structure
mov.w
_PPark_qVd,VdW
mov.w
_PPark_qVq,VqW
;; Get qSin, qCos from ParkParm structure
mov.w
_PPark_qSin,SinW
mov.w
_PPark_qCos,CosW
;; Valpha = Vd*cos(Angle) - Vq*sin(Angle)
mpy
CosW*VdW,A
; Vd*qCos -> A
msc
SinW*VqW,A
; sub Vq*qSin from A
mov.w
#_PPark_qValpha,ParmW
sac
A,[ParmW++]
; store to qValpha, inc ptr to qVbeta
;; Vbeta = Vd*sin(Angle) + Vq*cos(Angle)
mpy
SinW*VdW,A
; Vd*qSin -> A
mac
CosW*VqW,A
; add Vq*qCos to A
sac
A,[ParmW]
; store to Vbeta
return
