Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet

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SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

The ADC Controller features automatic comparison functions. It compares converted values to a low threshold or a high
threshold or both, according to the CMPMODE function chosen in the Extended Mode Register (ADC_EMR).
The comparison can be done on all channels or only on the channel specified in CMPSEL field of ADC_EMR.
To compare all channels the CMP_ALL parameter of ADC_EMR should be set. 

The flag can be read on the COMPE bit of the Interrupt Status Register (ADC_ISR) and can trigger an interrupt.

The High Threshold and the Low Threshold can be read/write in the Comparison Window Register (ADC_CWR). 

If the comparison window is to be used with LOWRES bit in ADC_MR set to 1, the thresholds do not need to be adjusted
as adjustment will be done internally. Whether or not the LOWRES bit is set, thresholds must always be configured
in consideration of the maximum ADC resolution.

Each ADC has its own minimal Startup Time that is programmed through the field STARTUP in the Mode Register,
ADC_MR.

A minimal Tracking Time is necessary for the ADC to guarantee the best converted final value between two channel
selections. This time has to be programmed through the TRACKTIM bit field in the Mode Register, ADC_MR.

Warning: No input buffer amplifier to isolate the source is included in the ADC. This must be taken into consideration
to program a precise value in the TRACKTIM field. See the product ADC Characteristics section.