33.4.2.2 Conversion Triggers

A conversion is started by one of the following triggers, depending on the configuration of the Start Conversion bit field in the Command register (COMMAND.START):

• Writing the IMMEDIATE value to COMMAND.START
  • This allows for software-controlled sampling
• Writing to the ADC Input Multiplexer Control (INPUTCTRL) register
  • This is useful when the ADC samples multiple inputs sequentially. When switching to the next input, the conversion automatically starts.
• Receiving an event input
  • This configuration allows the ADC to start automatically, either when a non-periodic event signals that a conversion is needed, or when a periodic event, such as the output from a timer, controls the sampling rate

Continuously repeating conversions or accumulations can be by setting the Free-running bit in the Control D register (CTRLD.FREERUN) to ‘1’ before starting the first conversion.

If a new conversion is triggered before the ongoing conversion has finished, the Trigger Overrun Interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.TRIGOVR) will be set, and the attempted trigger will be ignored.