F28335内部集成了一块ADC转换模块。核心是一个12位精度的模数转换器。ADC模块一般都是非常昂贵的，但是有时候我们必须要转换好几个信号，可是这样就需要接多个模数芯片，这样是非常昂贵的，所以一般都是采用分时复用。在F28335中通过多时复用产生了16个输入通道。只有一个转换器肯定不可能同时进行16路转换，此时就是时间换资源，并且在内部还有两个采样保持器，这两个采样保持器肯定也不可能同转换，也是分时的。ADCAIN0~ADCAIN7的某个端口，比如ADCAIN4采到的电压，先存入S/H-A，ADCBIN0~ADCBIN7的某个端口，比如ADCBIN3采到的电压，先存入S/H-B，然后S/H-A的结果传到转换核心进行转换，结果存到Result Reg 0中，S/H-B的结果传到转换核心进行转换，结果存到Result Reg 1中，然后继续进行别的转换。而转换的顺序则是由两个排序器决定的。比如可以A0->A5->A2->A0->A1等等，当ADC接收到触发源的开始转换信号（SOC）就根据排序器自动完成多路转换，转换的结果也是依次存入结果寄存器中。

ADC有多个触发源可以启动转换（SOC）
1.S/W-软件立即启动
2.外部引脚
3.ePWMx SOCA启动
4.ePWMx SOCB启动
而且允许每个或者每隔一个序列转换结束就可以产生中断，方便读取数据。 最后上一个官方例程吧 //########################################################################### // Description //! addtogroup f2833x_example_list //!

ADC Start of Conversion (adc_soc)

//! //! This ADC example uses ePWM1 to generate a periodic ADC SOC on SEQ1. //! Two channels are converted, ADCINA3 and ADCINA2. //! //!  Watch  Variables //! - Voltage1[10] - Last 10 ADCRESULT0 values //! - Voltage2[10] - Last 10 ADCRESULT1 values //! - ConversionCount - Current result number 0-9 //! - LoopCount - Idle loop counter // // //########################################################################### // $TI Release: F2833x/F2823x Header Files and Peripheral Examples V141 $ // $Release Date: November 6, 2015 $ // $Copyright: Copyright (C) 2007-2015 Texas Instruments Incorporated - // http://www.ti.com/ ALL RIGHTS RESERVED $ //########################################################################### #include "DSP28x_Project.h" // Device Headerfile and Examples Include File // Prototype statements for functions found within this file. __interrupt void adc_isr(void); // Global variables used in this example: Uint16 LoopCount; Uint16 ConversionCount; Uint16 Voltage1[10]; Uint16 Voltage2[10]; main() { // Step 1. Initialize System Control: // PLL, WatchDog, enable Peripheral Clocks // This example function is found in the DSP2833x_SysCtrl.c file. InitSysCtrl(); EALLOW; #if (CPU_FRQ_150MHZ) // Default - 150 MHz SYSCLKOUT #define ADC_MODCLK 0x3 // HSPCLK = SYSCLKOUT/2*ADC_MODCLK2 = 150/(2*3) = 25.0 MHz #endif #if (CPU_FRQ_100MHZ) #define ADC_MODCLK 0x2 // HSPCLK = SYSCLKOUT/2*ADC_MODCLK2 = 100/(2*2) = 25.0 MHz #endif EDIS; // Define ADCCLK clock frequency ( less than or equal to 25 MHz ) // Assuming InitSysCtrl() has set SYSCLKOUT to 150 MHz EALLOW; SysCtrlRegs.HISPCP.all = ADC_MODCLK; EDIS; // Step 2. Initialize GPIO: // This example function is found in the DSP2833x_Gpio.c file and // illustrates how to set the GPIO to it's default state. // InitGpio(); // Skipped for this example // Step 3. Clear all interrupts and initialize PIE vector table: // Disable CPU interrupts DINT; // Initialize the PIE control registers to their default state. // The default state is all PIE interrupts disabled and flags // are cleared. // This function is found in the DSP2833x_PieCtrl.c file. InitPieCtrl(); // Disable CPU interrupts and clear all CPU interrupt flags: IER = 0x0000; IFR = 0x0000; // Initialize the PIE vector table with pointers to the shell Interrupt // Service Routines (ISR). // This will populate the entire table, even if the interrupt // is not used in this example. This is useful for debug purposes. // The shell ISR routines are found in DSP2833x_DefaultIsr.c. // This function is found in DSP2833x_PieVect.c. InitPieVectTable(); // Interrupts that are used in this example are re-mapped to // ISR functions found within this file. EALLOW; // This is needed to write to EALLOW protected register PieVectTable.ADCINT = &adc_isr; EDIS; // This is needed to disable write to EALLOW protected registers // Step 4. Initialize all the Device Peripherals: // This function is found in DSP2833x_InitPeripherals.c // InitPeripherals(); // Not required for this example InitAdc(); // For this example, init the ADC // Step 5. User specific code, enable interrupts: // Enable ADCINT in PIE PieCtrlRegs.PIEIER1.bit.INTx6 = 1; IER |= M_INT1; // Enable CPU Interrupt 1 EINT; // Enable Global interrupt INTM ERTM; // Enable Global realtime interrupt DBGM LoopCount = 0; ConversionCount = 0; // Configure ADC AdcRegs.ADCTRL1.bit.ACQ_PS = ADC_SHCLK;//顺序采样方式 AdcRegs.ADCTRL3.bit.ADCCLKPS = ADC_CKPS;//ADC工作25Mhz，不再分频 AdcRegs.ADCTRL1.bit.SEQ_CASC = 1; // 1通道模式，级联 AdcRegs.ADCTRL1.bit.CONT_RUN = 1; // Setup continuous run AdcRegs.ADCMAXCONV.all = 0x0001; // Setup 2 conv's on SEQ1 AdcRegs.ADCCHSELSEQ1.bit.CONV00 = 0x3; // Setup ADCINA3 as 1st SEQ1 conv. AdcRegs.ADCCHSELSEQ1.bit.CONV01 = 0x2; // Setup ADCINA2 as 2nd SEQ1 conv. AdcRegs.ADCTRL2.bit.EPWM_SOCA_SEQ1 = 1;// Enable SOCA from ePWM to start SEQ1 AdcRegs.ADCTRL2.bit.INT_ENA_SEQ1 = 1; // Enable SEQ1 interrupt (every EOS) // Assumes ePWM1 clock is already enabled in InitSysCtrl(); EPwm1Regs.ETSEL.bit.SOCAEN = 1; // Enable SOC on A group EPwm1Regs.ETSEL.bit.SOCASEL = 4; // Select SOC from from CPMA on upcount EPwm1Regs.ETPS.bit.SOCAPRD = 1; // Generate pulse on 1st event EPwm1Regs.CMPA.half.CMPA = 0x0080; // Set compare A value EPwm1Regs.TBPRD = 0xFFFF; // Set period for ePWM1 EPwm1Regs.TBCTL.bit.CTRMODE = 0; // count up and start // Wait for ADC interrupt for(;;) { LoopCount++; } } __interrupt void adc_isr(void) { Voltage1[ConversionCount] = AdcRegs.ADCRESULT0 >>4; Voltage2[ConversionCount] = AdcRegs.ADCRESULT1 >>4; // If 40 conversions have been logged, start over if(ConversionCount == 9) { ConversionCount = 0; } else { ConversionCount++; } // Reinitialize for next ADC sequence AdcRegs.ADCTRL2.bit.RST_SEQ1 = 1; // Reset SEQ1 AdcRegs.ADCST.bit.INT_SEQ1_CLR = 1; // Clear INT SEQ1 bit PieCtrlRegs.PIEACK.all = PIEACK_GROUP1; // Acknowledge interrupt to PIE return; }