40.5.2.2 Operation

As stated previously, the ADC performs a sample and hold followed by a conversion. The conversion can occur manually via Hardware (CTRLB.SWCNVEN = 0), or through Software Control (CTRLB.SWCNVEN = 1).

A trigger event initiates the start of the ADC sampling of the selected analog input. After the expiration of the SAMC sample time the conversion sequence is automatically initiated by the hardware or waits for the software. Either can be fast for a single channel.

Multiple channels are sequentially sampled in the case of SCAN mode. To obtain maximum efficiency, at the conclusion of the sampling for the current active analog input, the analog multiplexer will switch to the next channel. This happens while the conversion cycle is in progress for the current input channel. This switch allows the next channel to be converted immediately after the current conversion is complete. In SCAN mode, sample/conversion progression is always lower to higher numbered channels as selected by the user in the CHNCFG2.CSSx register.