例程adc_soc_continuous_dma中主要对A3，B3同时采集， SetupADCContinuous(&AdcaRegs, 3)此函数中把16个ADCSOCCTL的通道都选择为3，不是很理解，麻烦解答下？
adcRegs->ADCSOC0CTL.bit.CHSEL = channel;
adcRegs->ADCSOC1CTL.bit.CHSEL = channel;
adcRegs->ADCSOC2CTL.bit.CHSEL = channel;
adcRegs->ADCSOC3CTL.bit.CHSEL = channel;
adcRegs->ADCSOC4CTL.bit.CHSEL = channel;
adcRegs->ADCSOC5CTL.bit.CHSEL = channel;
adcRegs->ADCSOC6CTL.bit.CHSEL = channel;
adcRegs->ADCSOC7CTL.bit.CHSEL = channel;
adcRegs->ADCSOC8CTL.bit.CHSEL = channel;
adcRegs->ADCSOC9CTL.bit.CHSEL = channel;
adcRegs->ADCSOC10CTL.bit.CHSEL = channel;
adcRegs->ADCSOC11CTL.bit.CHSEL = channel;
adcRegs->ADCSOC12CTL.bit.CHSEL = channel;
adcRegs->ADCSOC13CTL.bit.CHSEL = channel;
adcRegs->ADCSOC14CTL.bit.CHSEL = channel;
adcRegs->ADCSOC15CTL.bit.CHSEL = channel;
