The ADC features a noise canceler that enables conversion during sleep mode to reduce noise induced from the CPU core and other I/O peripherals. The noise canceler can be used with ADC Noise Reduction and Idle mode. To make use of this feature, the following procedure should be used:
- Make sure that the ADC is enabled and
is not busy converting. Single Conversion mode must be selected and the ADC conversion
complete interrupt must be enabled.
- Enter ADC Noise Reduction mode (or Idle
mode). The ADC will start a conversion once the CPU has been halted.
- If no other interrupts occur before the
ADC conversion completes, the ADC interrupt will wake up the CPU and execute the ADC
Conversion Complete interrupt routine. If another interrupt wakes up the CPU before the
ADC conversion is complete, that interrupt will be executed, and an ADC Conversion
Complete interrupt request will be generated when the ADC conversion completes. The CPU
will remain in active mode until a new sleep command is executed.
Note: The ADC will not be automatically turned off when entering other sleep modes than Idle
mode and ADC Noise Reduction mode. The user is advised to write zero to ADCRSA.ADEN before
entering such sleep modes to avoid excessive power consumption.