位单片机原理及应用基于pic32mx1xx2xx系列便携式实验开发板配套光盘daad example

13.8由输出构成DA模拟量输出和将其采样的AD例本节描述了在微芯PIC32MX220F032B型上的DA-AD综合示例。通过输出占空比从0~100%渐8段数码管显示（0～1023适用范围：本节所描述的代码适用于PIC32MX220F032B型（28引脚SOIC封装对于其他型号或封装的，测试，不确定其可用性。13-2SPIA/D1由SPI模块自动选择(SCK2只能选这个引脚SPI2PPSOutput(2,RPB8,SPI34RPB7Rbits.RPB7R=52ANSELAbits.ANSA0=基于的D/A变换电路：采用PIC32MX220F032B型所具有的脉宽调制通道输出可变占空比的波形，将波形通过RC滤波电路将其形成大小可调的模拟量，即可实现D/A13-6 13-6RC10D/AA/D转换模块将其电压值转换成数字量送到LED开 开 否是否缓冲区指否是否缓冲区指针将缓冲区数据求和取平int{intint{int{if(ADS_flag>{ADS_flag=adrst[adptr]= if(adptr>15){adptr=ads=ads+=adrst[i];ads=ads>>4;}}}return}开 开 联开开启动AD采返结返结 init函数流程框图图13-9：定时器中断函数流程框图图13-10 { RPB7Rbits.RPB7R= 1OC1CON=1//TurnoffOC1ng //InitializesecondaryCompareOC1CON=//2周期设定+//ConfigurePR2 //SetT2CONSET= //Enable 1init函数例程（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采样函数例程（13-10所示UINT16 {{//自动采样：31Tadwhile //= //结束本次采样/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字库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; //自动采样：31个Tad后自动转换while(!AD1CON1bits.DONE); //等待转换完成AD1CON1bits.ASAM=0; //结束本次采样/转换操作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周期设定+PR2 //SetT2CONS