Channel Selection

The ADPCH and ADNCH registers determine which input channels are connected to the Sample-and-Hold circuit for conversion. When switching channels, it is recommended to have some acquisition time (ADACQ register) before starting the next conversion. Refer to the ADC Operation section for more information.

Important: To reduce the chance of measurement error, it is recommended to discharge the Sample-and-Hold capacitor when switching between ADC channels by starting a conversion on a channel connected to VSS and terminating the conversion after the acquisition time has elapsed. If the ADC does not have a dedicated VSS input channel, the VSS selection through the DAC output channel can be used. If the DAC is in use (or the device does not have a DAC), a free input channel can be connected to VSS, and can be used in place of the DAC.