13.8由輸出構(gòu)成DA模擬量輸出和將其采樣的AD例本節(jié)描述了在微芯PIC32MX220F032B型上的DA-AD綜合示例。通過輸出占空比從0~100%漸8段數(shù)碼管顯示（0～1023適用范圍：本節(jié)所描述的代碼適用于PIC32MX220F032B型（28引腳SOIC封裝對于其他型號或封裝的，測試，不確定其可用性。13-2SPIA/D1由SPI模塊自動選擇(SCK2只能選這個引腳SPI2PPSOutput(2,RPB8,SPI34RPB7Rbits.RPB7R=52ANSELAbits.ANSA0=基于的D/A變換電路：采用PIC32MX220F032B型所具有的脈寬調(diào)制通道輸出可變占空比的波形，將波形通過RC濾波電路將其形成大小可調(diào)的模擬量，即可實(shí)現(xiàn)D/A13-6 13-6RC10D/AA/D轉(zhuǎn)換模塊將其電壓值轉(zhuǎn)換成數(shù)字量送到LED開 開 否是否緩沖區(qū)指否是否緩沖區(qū)指針將緩沖區(qū)數(shù)據(jù)求和取平int{intint{int{if(ADS_flag>{ADS_flag=adrst[adptr]= if(adptr>15){adptr=ads=ads+=adrst[i];ads=ads>>4;}}}return}開 開 聯(lián)開開啟動AD采返結(jié)返結(jié) init函數(shù)流程框圖圖13-9：定時器中斷函數(shù)流程框圖圖13-10 { RPB7Rbits.RPB7R= 1OC1CON=1//TurnoffOC1ng //InitializesecondaryCompareOC1CON=//2周期設(shè)定+//ConfigurePR2 //SetT2CONSET= //Enable 1init函數(shù)例程（13-8所示OC1CONSETOC1CONSET=//Enable}//ConfiguretheTimer//ConfiguretheTimer1interruptvoidISR(_TIMER_1_VECTOR,ipl2){//Cleartheinterruptflag{t> t=ADS_flag=}{t>t= 1_d=={1 1>DUTYMAX{1=1_d=}}{ 1=={1=1_d=}1--} }}4、AD采樣函數(shù)例程（13-10所示UINT16 {{//自動采樣：31Tadwhile //= //結(jié)束本次采樣/return }附件：代* #include//ConfigurationBit//SYSCLK=48MHz(8MHzCrystal/FPLLIDIV*FPLLMUL///PBCLK=48MHz(SYSCLK///PrimaryOscw/PLL//WDT#pragmaconfigFPLLMUL=MUL_24,FPLLIDIV=DIV_2,FPLLODIV=DIV_2,FWDTEN=OFF#pragmaconfigPOSCMOD=HS,FNOSC=FRCPLL,FPBDIV=DIV_1#pragmaconfigFUSBIDIO //FUSBIDIO#pragmaconfig = //Periodneededfortimer1totriggeraninterruptevery0.1//(48MHzPBCLK/1 KHzTimer1#definePERIOD =0.001s=0.2ms#defineBTN_DELAY //2*5=10ms#defineSYS_FREQ( #defineDUTYMAX0x0DFF unsignedint unsignedintadrst[16]={0},adptr=0;//0~9,0.~9.FSEt-unsignedcharLed_lib[]={0x42,0xf3,0x86,0xa2,0x33,0x2a,0x0a,0xf2,0x02,0x22,0x40,0xf1,0x84,0xa0,0x31,0x28,0x08,0xf0,0x00,0x20,0x1e,0x0e,0x0f,0xbf,0x23,0x9b,0x8b};//LED字庫voidSpiInitDevice()//8bits/char,inputdatasampledatendofdataoutputSpiOpenFlagsoFlags=SPI_OPEN_MSTEN|SPI_OPEN_CKP_HIGH|SPI_OPEN_MODE8|PPSOutput(2,RPB8,SDO2);//SetRB8pinasoutputfor//OpenSPImodule,useSPIchannel2,useflagssetabove,DivideFpbby6SpiChnOpen(2,oFlags,6);}voidSpiDoBurst(unsignedchar*pBuff,unsignedcharLen){if(pBuff){unsignedintfor(i=0;i<Len;i++){}}}void{= PORTA.0AN0AD1CON1 //AD1CHS CH0CH1AN0AD1CSSL=AD1CON3 //AD1CON2 //VREF+VREF-//2= //}UINT16{AD1CON1bits.ASAM=1; //自動采樣：31個Tad后自動轉(zhuǎn)換while(!AD1CON1bits.DONE); //等待轉(zhuǎn)換完成AD1CON1bits.ASAM=0; //結(jié)束本次采樣/轉(zhuǎn)換操作return }{spibuff[2]=Led_lib[rst%10]; spibuff[1]=Led_lib[(rst/10)%10]; spibuff[0]=Led_lib[(rst/100)%10]; spibuff[3]=Led_lib[rst/1000]; }void{//OpenTimer1(T1_ON|T1_SOURCE_INT|T1_PS_1_1,//Setupthetimerinterruptwithapriorityof2INTEnable(INT_T1,INT_ENABLED);}//ConfiguretheTimer1interruptvoidISR(_TIMER_1_VECTOR,ipl2){//Cleartheinterruptflag t> {t=ADS_flag=} t>{t= 1_d=={1 1>DUTYMAX{}}{

1=1_d= 1=={}}

1=1_d=1-- }} {RPB7Rbits.RPB7R=RPB7Rbits.RPB7R=1//1初始OC1CON=//offOC1ng //InitializesecondaryCompareOC1CON= //Configure //2周期設(shè)定+PR2 //SetT2CONS