Motorola MCU 68HC912 Manual do Utilizador descarregar pdf (Página 12)

SLAA108A

12 SPI-Based Data Acquisition/Monitor Using the TLC2551 Serial ADC

LOOP:

LSRD ; R Shift ACCD

DBNE X,LOOP ; Loop 4 times

STAA UPPER_BYTE ; Store shifted data

STAB LOWER_BYTE ; Store shifted data

;* ----------------------------------------------------------------------

;* Transmit Subroutine

;* ----------------------------------------------------------------------

MOVB #$80, PORTS ; ADC CS Hi

BSET PORTS, #%00001000 ; Set FS to DAC(PS3) Hi

BCLR PORTS, #%00001000 ; Set FS to DAC(PS3) Lo

MOVB UPPER_BYTE, SP0DR ; Load Data Register with Upper Byte

BSR FLAG

MOVB LOWER_BYTE, SP0DR ; Load Data Register with Upper Byte

BSR FLAG

MOVB #$00, SP0DR ; Load Data Register with Zero

BSR FLAG

MOVB #$00, SP0DR ; Load Data Register with Zero

BSR FLAG

BRA SAMPLE ; Go back and do it again

;* -------------------------------------------

;* Clear SPIF

;* -------------------------------------------

FLAG:

BRCLR SP0SR,#$80,FLAG ; Wait for flag.

RTS

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Motorola MCU 68HC912 Manual do Utilizador Página 12