利用 DAC 介面生成方波
我們編寫一個使用數字模擬轉換器 (DAC) 介面生成矩形波干擾的程式
讓我們考慮該領域的某個問題解決方案。該問題說明:為了獲得單極性輸出,在介面上講 J1 短路到 J2。為了在 CRO 上顯示波形,將聯結器 P1 的引腳 1 連線到 CRO 訊號引腳,將聯結器 P1 的引腳 2 連線到 CRO 接地引腳。
程式如下所示。
; 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
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