Listing 1 for DI #2312:
"uC reprograms audio DAC via serial interface"
by Lukasz Sliwczynski, University of Mining and Metallurgy, Institute of Electronics, Cracow, Poland.

****************************************************************


; ATTENUATION SET ON PORT P1.0 (MSB) - P1.6 (LSB)
.EQU PCON, 087H
.EQU FLAG.7, 07H
.EQU FLAG.6, 06H
.EQU FLAG.5, 05H


.ORG 00H
	JBC FLAG.7,B_03		;2
	JBC FLAG.6,B_02		;2 -> TOTAL MACHINE CYCLES: 4

B_01:	MOV SBUF,R0		;2 SEND ATTENUATION BYTE
	MOV R0,#25H		;1 SAVE MODE 2 BYTE BEFORE RESET
	SETB FLAG.6		;1 SET UP FOR THE NEXT RESET
	MOV A,#02H		;1
	NOP			;1
	NOP			;1
	NOP			;1
	NOP			;1
	NOP			;1
	CLR P3.2		;1 GENERATE ML SIGNAL
	ORL PCON,A 		;1 GO TO POWER DOWN -> TOTAL MACHINE CYCLES: 12

B_02:	MOV SBUF,R0		;2 SEND BYTE MODE 2
	MOV A,P1		;1 READ MUTE SIGNAL FROM P1.7
	ANL A,#080H		;1
	ORL A,#060H		;1
	MOVC A,@A+DPTR	;2 CALCULATE ADDRESS OF MODE 1 BYTE
	MOV R0,A		;1 SAVE MODE 1 BYTE BEFORE RESET
	SETB FLAG.7		;1 SET UP FOR THE NEXT RESET
	MOV A,#02H		;1
	CLR P3.2		;1 GENERATE ML SIGNAL
	ORL PCON,A		;1 GO TO POWER DOWN

B_03:	MOV SBUF,R0		;2 SEND BYTE MODE 1
	MOV A,P1		;1 READ ATTENUATION FROM PORT P1.0 - P1.6
	RL A			;1
	ANL A,#0FEH		;1
	MOV R0,A		;1 SAVE ATTENUATION VALUE BEFORE RESET
	SETB FLAG.5		;1 SET UP FOR THE NEXT RESET
	MOV A,#02H		;1
	NOP			;1
	NOP			;1
	CLR P3.2		;1 GENERATE ML SIGNAL
	ORL PCON,A		;1 GO TO POWER DOWN

;MODE 1 BYTE FOR MUTE-OFF -> P1.7 = L
.ORG 060H
	.DB 001H

;MODE 1 BYTE FOR MUTE-OFF -> P1.7 = H
.ORG 0E0H
	.DB 041H