试验五ad转换.doc

试验五 A/D转换一、 试验目的：1、 学习用单片机上的A/D模块实现电压或电流的测量方法2、 学习基于MPLAB用PICC进行编程和调试。二、 试验参考程序#include#include#includeextern void init_sys(void);extern void Display(void);unsigned int a;unsigned int b;unsigned int Num_t;unsigned int Num_one;unsigned int ADBUFF;unsigned int whole;void init_sys(void) /单片机初始化程序asm(CLRWDT);TRISA=0xff;TRISB=0xff;TRISC=0;TRISD=0;TRISE1=0xff;T1CON=0b0011001; /时钟源：Fosc/4;8分频；ADCON0= 0b10000101; /ADCON0和ADCON1的设置请参考教材ADCON1=0b00000100;/下面设置使能TMR1中断的三个使能控制位GIE=1;PEIE=1;TMR1IE=1;ADIE=1;Num_t=0;void interrupt interr(void) /这是中断子程序，其中“void interrupt”是专门申明中断子程/序类型的if(TMR1IF)TMR1IF=0; /清中断标志位 GODONE=1; /将ADCON0寄存器的GO/DONE位置1，启动A/D转换asm(CLRWDT); /这是一句在C程序中混编汇编程序的例子if(ADIF)ADIF=0;ADBUFF=ADRESH; /保存高8位AD结果 a=ADBUFF/51; /A=(ADRES/B11111111)*Vref=(ADRES/255)*5= ADRES/51/注意：运算结果小数部分是舍弃的，这可以帮助大家理解此程 /序 b=ADBUFF*10/51-10*a;Display(); void Display(void)/下面设置十位，个位的代码,请结合电路图理解七段数码管的显示代码的设定switch (a) case 0:Num_t=0b00000001;break;case 1:Num_t=0b01011101;break;case 2:Num_t=0b00010010;break;case 3:Num_t=0b00011000;break; case 4:Num_t=0b01001100;break; case 5: Num_t=0b10001000;break; default: break; PORTC=Num_t; switch (b) case 0:Num_one=0b00100001;break;case 1:Num_one=0b01111101;break;case 2:Num_one=0b00110010;break;case 3:Num_one=0b00111000;break; case 4:Num_one=0b01101100;break; case 5: Num_one=0b10101000;break; case 6:Num_one=0b10100000;break;case 7:Num_one=0b00111101;break; case 8:Num_one=0b00100000;break; case 9: Num_one=0b00101000;break; default: break; PORTD=Num_one;void main(void)init_sys();while(1)asm(nop); 三、电路原理图： INCLUDEP16f877a.incADRES EQU 0X23 ;A BUFFER TO SAVE A/D RESULTINTCNTEQU 0X24;A BUFFER TO SAVE A/D TIMES;下面这些寄存器是用来进行除法的ACCALOEQU 0X25ACCAHIEQU 0X26ACCBLOEQU 0X27ACCBHIEQU 0X28ACCCLOEQU 0X29ACCCHIEQU 0X2AACCDLOEQU 0X2BACCDHIEQU 0X2CTEMPEQU 0X2DSIGNEDEQU 0 ORG 0x00 GOTO START ORG 0x04 BTFSC INTCON,T0IF ; Test T0 Interrupt Flag CALL TMR0_ISR ;T0 Interrupt Service Routine BTFSC PIR1,ADIF ; Test A/D Interrupt Flag CALL AD_ISR ; A/D Interrupt Service RoutineRETFIE START: CALL PIC_INIT ; PIC Initialization MAIN_LOOP:NOPNOPNOP NOP GOTO MAIN_LOOP;以下是二进制除法D_DIVS: IF SIGNED CALL S_SIGN ENDIFCALL SETUPCLRF ACCCHICLRF ACCCLOLOOP: BCF STATUS,CRLF ACCDLORLF ACCDHIRLF ACCCLORLF ACCCHIMOVF ACCAHI,WSUBWF ACCCHI,W ;check if acBTFSS STATUS,ZGOTO NOCHKMOVF ACCALO,WSUBWF ACCCLO,W ;if msb equal then check lsbNOCHK: BTFSS STATUS,C ;carry set if caGOTO NOGOMOVF ACCALO,W ;c-a into cSUBWF ACCCLOBTFSS STATUS,CDECF ACCCHIMOVF ACCAHI,WSUBWF ACCCHIBSF STATUS,C ;shift a 1 into b (result)NOGO: RLF ACCBLORLF ACCBHIDECFSZ TEMP ;loop untill all bits checkedGOTO LOOP IF SIGNEDBTFSS SIGN,MSB ; check sign if negativeRETLW 0GOTO NEG_B ; negate ACCa ( -ACCa - ACCa ) ELSERETLW 0 ENDIFSETUP: MOVLW .16 ; for 16 shiftsMOVWF TEMPMOVF ACCBHI,W ;move ACCb to ACCdMOVWF ACCDHIMOVF ACCBLO,WMOVWF ACCDLOCLRF ACCBHICLRF ACCBLORETLW 0NEG_A: COMF ACCALO ; negate ACCa ( -ACCa - ACCa )INCF ACCALOBTFSC STATUS,ZDECF ACCAHICOMF ACCAHIRETLW 0 IF SIGNEDS_SIGN MOVF ACCAHI,WXORWF ACCBHI,WMOVWF SIGNBTFSS ACCBHI,MSB ; if MSB set go & negate ACCbGOTO CHECK_ACOMF ACCBLO ; negate ACCbINCF ACCBLOBTFSC STATUS,ZDECF ACCBHICOMF ACCBHICHEK_A BTFSS ACCAHI,MSB ; if MSB set go & negate ACCaRETLW 0GOTO NEG_A ENDIF;-;以上是定标程序;-PIC_INIT:BCFSTATUS,RP0CLRF INTCNT CLRF INTCON BSF STATUS , RP0 MOVLW B11000101 MOVWF OPTIONR ;设置TIMER0工作模式 MOVLW B11111111 MOVWF TRISA ;RA口为输入端口，以便其部分管脚为 A/D 输入管脚 MOVLW B00000000 MOVWF TRISB ；为显示结果，先将RB、RC口设为输出端口 MOVWF TRISCBCF STATUS,RP0CLRF PORTBCLRF RCBSF STATUS,RP0MOVLW B00000010 ; 设置A/D工作模式 MOVWF ADCON1 ;BCF STATUS,RP0MOVWF ADCON1 BSF INTCON,T0IE BSF PIE1,ADIE BCF STATUS,RP0 ; Choose Bank0 MOVLW B01001001 ; f/8, CH1, A/D on MOVWF ADCON0 BSF INTCON,PEIE ; ; Enable Peripheral Interrupt BSF INTCON,GIE ; Turn on Global Interrupn EnableRETURN TMR0_ISR: BCF STATUS,RP0 INCF INTCNT,FBCF INTCON,TOIF ; Clear Interrupt Flag BSF ADCON0,GO ; Trigger A/D CALLISR_ENDRETURNAD_ISR:BCF STATUS,RP0BCF PIR1,ADIFMOVF INTCNT,WSUBLW .10 BTFSS STATUS,ZRETURNBCF STATUS,RP0CLRF INTCNT BCF PIR1,ADIF ; Clear InterrupE Flag MOVF A_DRES,W MOVWF ADRES ; Store ValueCALL DISPLAY RETURN; 以下A/D转换结果定标和显示程序结果显示DISPLAY: MOVF ADRES,WMOVWF ACCBLOCLRF ACCBHIMOVLW .50MOVWF ACCALOCLRF ACCAHICALL D_DIVSMOVF ACCBLO,WCALL CHAR_CODEMOVWF PORTBBCF PORTB,5MOVF ACCCLO,WMOVWF ACCBLOCLRF ACCBHIMOVLW .5MOVWF ACCALOCLRF ACCAHICALL D_DIVSMOVF ACCBLO,WCALL CHAR_CODEMOVWF RCRETURN;以下数码管查表CHAR_CODE:ADDWF PCL,F RETLW B00100001 ; Code for 0 RETLW B01111101 ; Code for 1 RETLW B00110010 ; Code for 2 RETLW B00111000 ; Code for 3 RETLW B01101100 ;