Freescale Semiconductor DRM079 Manuel d'utilisateur télécharger pdf (Page 28)

Implementation

Variable Speed DC Fan Control using the MC9RS08KA2, Rev. 0

28 Freescale Semiconductor

sta KBIES ;HALL rising Edge Trigger

sta KBIPE ;KBI Enable

;-------------------------------------------------------

;Config MTIM

;

;Timer prescalar=256 -> Timer clk = 16kHz

;Bus = 4MHz

;Max OF period = 16.384ms

;Timer resolution = 64us

;-------------------------------------------------------

mov #(MTIM_BUS_CLK|MTIM_DIV_256), MTIMCLK

mov #255, MTIMMOD

;-------------------------------------------------------

;Motor Start Sequence

;-------------------------------------------------------

ResetPosition:

mov #mPWM1, PTAD ; Lock FAN in reset position

lda #30 ;

Dly1 bsr Delay ; for Delay 0.5s

dbnza Dly1 ;

clr PTAD ; de-energize coils

bsr Delay

; Drive L2

ldx #mPWM2 ; Select L2 Coils

bsr SetPWM ; Drive coil

bsr Delay ; De-energize coils

inc MotorRunning ; otherwise Update Software flag

;-------------------------------------------------------

;Fan Control Loop

;-------------------------------------------------------

FanControlLoop:

;1) Drive L1 coil

clr KBIES ; HALL falling edge trigger

ldx #mPWM1 ; Select L1 Coil

bsr SetPWM ; Drive coil

;2) Read Temp Sensor

jsr ReadSensor ; Read Sensor value

;3) Dead time control

StartTimer ; Wait dead time period

wait

mov #(mMTIMSC_TSTP|mMTIMSC_TRST), MTIMSC; mask interrupt and clear flag

;4) Drive L2 coil

bset HALL, KBIES ; HALL rising edge trigger

ldx #mPWM2 ; Select L2 Coil

bsr SetPWM ; Drive coil

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Freescale Semiconductor DRM079 Manuel d'utilisateur Page 28

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