ds1620.asm

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;#############################################################
;# PROCEDURY pro komunikaci s teplotnim cidlem Dallas DS1620 #
;#############################################################
;
.equ	RST_SPI, 0x90	; P1.0
.equ	CLK_SPI, 0x91	; P1.1
.equ	DQ_SPI,  0x92	; P1.2

.global init_ds1620
.global read_ds1620

	.comm	lasttemp, 1

	.text
	.using	0

read_ds1620:
	clr	RST_SPI		; drop reset
	setb	CLK_SPI		; raise clock
	setb	DQ_SPI		; make DQ1620 an input
	setb	RST_SPI		; raise reset
	mov	a,#0xEE		; CMD: Start Convert
	lcall	spiout		; send it to DS1620
	clr	RST_SPI		; drop reset

	mov	dptr,#0x0100	; timeout
Lcnvprg:inc	dptr
	mov	a,dph
	jz	Lcnvtimeout
	setb	RST_SPI		; raise reset
	mov	a,#0xAC		; CMD: Read Config
	lcall	spiout		; send it to DS1620
	lcall	spiin		; get status from ds1620
	clr	RST_SPI		; drop reset
	jnb	acc.7,Lcnvprg	; Conversion in progress

Lcnvgo:	nop
	nop
	setb	RST_SPI		; raise reset
	mov	a,#0xAA		; CMD: Read Temperature
	lcall	spiout
	lcall	spiin		; get temp data from ds1620 ( LSB )
	mov	r3,a		; move (LSB) of temp data to Storage Register.
	lcall	spiin		; get temp data from ds1620 ( MSB )
	clr	RST_SPI		; drop reset
	anl	a,#1
	jz	Lpositivetemp
	mov	a,r3
	add	a,#50
	jc	Lminus50
	clr	a
Lminus50:mov	lasttemp,a
	mov	a,r3
	cpl	a
	inc	a
	mov	r3,a
	mov	a,#'-'
	sjmp	Lsendtemp
Lpositivetemp:
	mov	a,r3
	add	a,#50
	jnc	Lplus103
	mov	a,#255
Lplus103:mov	lasttemp,a
	mov	a,#'+'
Lsendtemp:
	push	ar3
	lcall	sendchar
	pop	acc
	push	acc
	clr	C
	rrc	a
	lcall	sendDecb
	mov	a,#'.'
	lcall	sendchar
	pop	acc
	rrc	a
	mov	a,#'0'
	jnc	Ltempe
	mov	a,#'5'
Ltempe:	lcall	sendchar
	ret

Lcnvtimeout:
	lcall	send_string
	.asciz	"Error"
	ret

	.section reset_device, #alloc

init_ds1620:
	clr	RST_SPI		; drop reset
	setb	CLK_SPI		; raise clock
	setb	DQ_SPI		; make DQ1620 an input
	mov	a,#0x0C		; CMD: Write config
	setb	RST_SPI		; raise reset
	lcall	spiout		; send it to DS1620
	MOV	A,#0x03		; set config byte = 3
				;  CPU mode, one shot
	lcall	spiout		; send it to DS1620
;
;&&& end of DS1620 &&&
;
	;; end