做減法時(shí)當(dāng)然要將數(shù)據(jù)放到工作寄存器里,但采樣后數(shù)據(jù)不一定放在工作寄存器里,完全可以放到片內(nèi)RAM里.
兩個(gè)數(shù)據(jù)要和一個(gè)值比較,這個(gè)值是什么類(lèi)型?如果是立即數(shù),當(dāng)然是在程序里,也就是在ROM里.

我是將兩個(gè)A/D口采樣的電壓值轉(zhuǎn)換成16進(jìn)制數(shù)分高8位,低8位放在4個(gè)寄存器里面,再和一個(gè)電壓(16進(jìn)制)比較,即相減!
            LD     Acc1,    #1 ; 1th channel
            LD     Acc0,    #6 ; 6 sample times
            CALL   AdcConvert
            LD     Acc0,    #6 ; 6 adjust number
            CALL   AdcDataAdjust
            CALL   AverageValue
            LD     CellVoltageL,   AverageValueL
            LD     CellVoltageH,   AverageValueH
            LD     Acc9,           CellVoltageL
            LD     Acc10,          CellVoltageH
;---------------
            LD     Acc1,    #0 ; 0th channel
            LD     Acc0,    #6 ; 6 sample times
            CALL   AdcConvert
            LD     Acc0,    #6 ; 6 adjust number
            CALL   AdcDataAdjust
            CALL   AverageValue
            LD     CellVoltageL,   AverageValueL
            LD     CellVoltageH,   AverageValueH
            LD     Acc7,           CellVoltageL
            LD     Acc8,           CellVoltageH
            SUB    Acc9,           Acc7
            SBC    Acc10,          Acc8
            SUB    Acc9,           #>41  ; 0.2v
            SBC    Acc10,          #<41
            JR     ULT,            CJV_Down_0v2
            INC    Counter_Up_0v2
          CP  Counter_Up_0v2,#2               ;                
               JR     ULT,       DCC_Exit  
               LD     Counter_OutputUp,       #51h  
               JR     CJV_Exit
              
CJV_Down_0v2:
               CLR    Counter_OutputUp
               CLR    Counter_Up_0v2
CJV_Exit:
               RET

這個(gè)一直在困擾我啊,心急如焚啊!