read_ad.asm

VCP201_CODE is a FPGA source code.

;===========================================
; File Name : Read_AD.asm
; VCP201 PSX2 ASIC
; Read A/D senser for 18 chennal
; Ver:1.0	XX-06-2000
;=============================================

Read_AD:
 	movlw	0x29
 	movwf	fsr
 	movlw	0x12		;18 count
 	movwf	temp_1
	clrf	adadr

copy_data: 		
	movf	addata,w
	movwf	indf
	incf	fsr,f
	incf	adadr,f
	decfsz	temp_1,f
	goto	copy_data
	return


;--------------------------------
; null_data:
;--------------------------------
null_data: 		
	movf	addata,W
	movwf	vr_null
	sublw	0xb0		;null-c0
	btfss	STATUS,C   	;<c0, Min value is 0xb0h
	goto	null_data1 	;NO
        movlw	0xb0          	;Yes, null=b0
       	goto	null_data2

null_data1:                      	;larger then b0
	movf	vr_null,W
	movlw	0x10
	subwf	vr_null,W 	;-0d

null_data2:
	movwf	indf        	;store data in null range
	incf	fsr,f
	incf	adadr,f
	decfsz	temp_1,f
	goto	null_data		
	return