使用 DAC 介面生成三角波


我們編寫了一個 8085 組合語言程式,使用數字模擬轉換器 (DAC) 介面生成三角波形。波形的顯示在示波器上可見。

讓我們在這個領域考慮一個問題解決方案。該問題指出:為了獲得單極輸出,介面上的 J1 短接到 J2。要將波形顯示在示波器上,將聯結器 P1 的 1 號引腳連線到示波器訊號引腳,將聯結器 P1 的 2 號引腳連線到示波器地線引腳。

程式

; FILE NAME DAC_TO_TRIANG.ASM
ORG C100H
X DW 00FFH ; the fall of rise and time I proportional directly to the value.

ORG C000H
PA EQU D8H
PB EQU D9H
PC EQU DAH
CTRL EQU DBH

MVI A, 88H
OUT CTRL ; Purpose to configure 8255 ports
; The next 7 instructions will generate rising portion of the triangular waveform.
; And it is done by sending to DAC through Port A values from 00H to FFH,
; in steps of 01. Also the increment will be done after a small time delay here.

LOOP: MVI A, 00H
ASCEND: OUT PA
PUSH PSW
CALL DELAY

POP PSW
INR A
JNZ ASCEND

DCR A ; Now A contents will be FFH

DESCEND: OUT PA
PUSH PSW

CALL DELAY

POP PSW
DCR A
CPI FFH
JNZ DESCEND

JMP LOOP
; These Subroutines are used only for the generation of delay
; which is proportional to all the contents of word located at X.

DELAY: LHLD X
AGAIN: DCX H
MOV A, H
ORA L
JNZ AGAIN
RET

更新於:2019-07-30

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