本帖最后由 blues_more 于 2015-1-5 20:48 编辑
一个由信号发生器发出的正弦信号，信号频率为220Hz（模仿交流电信号频率，因为最终要采样交流电），方法是将数据由串口传PC，然后matlab绘图，但是结果波形有失真。主要程序和绘图结果如下。请问是什么原因呢？
Configure ADC
AdcRegs.ADCTRL1.bit.ACQ_PS = ADC_SHCLK;
AdcRegs.ADCMAXCONV.all = 0; // Setup 2 conv's on SEQ1
AdcRegs.ADCCHSELSEQ1.bit.CONV00 = 0x3; // Setup ADCINA3 as 1st 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 = 01; // Generate pulse on 1st event
EPwm1Regs.CMPA.half.CMPA = 0x0080;
EPwm1Regs.TBPRD = 0x1D4B; // Set period for ePWM1
EPwm1Regs.TBCTL.bit.CTRMODE = 00; // count up and start
interrupt void adc_isr(void)
{
VoltageH[ConversionCount] = AdcRegs.ADCRESULT0 >>12;
VoltageL[ConversionCount] = AdcRegs.ADCRESULT0 >>4;
// If 40 conversions have been logged, start over
if(ConversionCount == 127)
{
for (ConversionCount=0;ConversionCount<128;ConversionCount++)
{
scib_xmit(VoltageH[ConversionCount]);
scib_xmit(VoltageL[ConversionCount]);
}
for(;;);
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;
}
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