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