Motorola MCU 68HC912 Manual do Utilizador descarregar pdf (Página 7)

SLAA108A

SPI-Based Data Acquisition/Monitor Using the TLC2551 Serial ADC 7

ADC_CS equ 001h ; Assign p3.1 to ADC_CS

FS equ 010h ; Assign p3.6 to FS (DAC and ADC)

DAC_CS equ 020h ; Assign p5.4 to DAC_CS

;************************************************************************

;Setup Stack

;************************************************************************

RSEG CSTACK

DS 0

;************************************************************************

;Program Code

;************************************************************************

RSEG CODE

;************************************************************************

RESET_ISR mov #SFE(CSTACK),SP ; define stackpointer

call #Init_Sys ; Initialize the MSP430

call #Mainloop ; Run the Main Program

Mainloop

Read_ADC bic.b #ADC_CS,&P3OUT

mov.b #DUMMY,&U0TXBUF ; Dummy write to SPI (generates SCLK)

call #CLEAR

mov.b &U0RXBUF,R12 ; Store Upper Byte

mov.b #DUMMY,&U0TXBUF ; Dummy write to SPI (generates SCLK)

call #CLEAR

mov.b &U0RXBUF,R13 ; Store Lower Byte

mov.b #04h, R7

CLK_LOOP mov.b #DUMMY,&U0TXBUF ; Dummy write to SPI

CONV_CLK bit.b #01h,&IFG2 ; TXBUF ready?

jnc CONV_CLK ; 1 = ready

bic.b #01h,&IFG2

dec R7

cmp #00h, R7

jnz CLK_LOOP

biC.b #ADC_CS,&P3OUT

; jmp Mainloop ; Repeat

; Remove remark from above line to skip transmit back to DAC

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Motorola MCU 68HC912 Manual do Utilizador Página 7