ADMA_CH_CMD
tdma_ch_write(tdc, ADMA_CH_CMD, 0);
tdma_ch_write(tdc, ADMA_CH_CMD, 1);
ch_reg->cmd = tdma_ch_read(tdc, ADMA_CH_CMD);
tdma_ch_write(tdc, ADMA_CH_CMD, ch_reg->cmd);