Programming: ADC (Analog to Digital Conversion) Using Multiple Channels

To select a channel of the ADC to use for input, the ADMUX must be set according to the channel that is used. The last 5 digits of the ADMUX register is used to select this channel.

For instance, if: ADMUX |= 0, then channel 0 is used ADMUX |= 1, then channel 1 is used and so on.