34.3.2.2 Starting a Conversion
When the ENABLE bit in the Control A (DACn.CTRLA) register is ‘1’, a conversion
            starts as soon as the Data (DACn.DATA) register is written.
When the ENABLE bit in DACn.CTRLA is ‘0’, writing to the Data register
            does not trigger a conversion. Instead, the conversion starts when the ENABLE bit in
            DACn.CTRLA is ‘1’.
