使用DAC接口生成矩形波

我们编写了一个程序来生成数模转换器(DAC)干扰的矩形接口：

让我们考虑这个领域的问题解决方案。问题指出：为了获得单极性输出，J1在接口上短接到J2。要在CRO上显示波形，请将连接器P1的引脚1连接到CRO信号引脚，并将连接器P1的引脚2连接到CRO接地引脚。

该程序说明如下。

; FILE NAME DAC_TO_RECT.ASM

ORG C100H

X DW 00FFH ; ‘OFF’ time is proportional to this value

Y DW 00C0H ; ‘ON’ time is proportional to this value

ORG C000H

PA EQU D8H

PB EQU D9H

PC EQU DAH

CTRL EQU DBH

MVI A, 88H

OUT CTRL ; Configure 8255 ports

LOOP: LHLD Y

XCHG

LHLD X ; Now DE contains 00C0H and HL contains 00FFH

MVI A, 00H

OUT PA ; Sending 00H to DAC through the Port A

CALL DELAY ; Generation of delay proportional to the contents of HL.

XCHG ; Now HL contains 00C0H

MVI A, FFH

OUT PA ; Sending the FFH to Digital to Analog Converter through Port A

CALL DELAY ; Generation of delay proportional to the contents of HL

JMP LOOP

; Subroutine to generate a delay proportional to contents of HL

DELAY: DCX H

MOV A, H

ORA L

JNZ DELAY

RET