利用 DAC 接口生成方波


我们编写一个使用数字模拟转换器 (DAC) 接口生成矩形波干扰的程序

 让我们考虑该领域的某个问题解决方案。该问题说明:为了获得单极性输出,在接口上讲 J1 短路到 J2。为了在 CRO 上显示波形,将连接器 P1 的引脚 1 连接到 CRO 信号引脚,将连接器 P1 的引脚 2 连接到 CRO 接地引脚。

程序如下所示。

; 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

更新于: 30-7-2019

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