SH7709_ADCSR_ADST
if ((csr & SH7709_ADCSR_ADST) != 0) {
ADC_(CSR) = chan | SH7709_ADCSR_ADST | SH7709_ADCSR_CKS;
csr &= ~(SH7709_ADCSR_ADF | SH7709_ADCSR_ADST);