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Figure 46-3. Single-Shot Example

GCLK_AC

STATUSB.READYx

Sampled

Comparator Output

CTRLB.STARTx

STARTUP

Write ‘1’

STARTUP

Write ‘1’

2-3 cycles 2-3 cycles

For low-power operation, event-triggered measurements can be performed during sleep modes. When

the event occurs, the Power Manager will start GCLK_AC. The comparator is enabled, and after the

startup time has passed, a comparison is done and appropriate peripheral events and interrupts are also

generated. The comparator and GCLK_AC are then disabled again automatically, unless configured to

wake up the system from sleep.

46.6.3 Selecting Comparator Inputs

Each comparator has one positive and one negative input. The positive input is one of the external input

pins (AINx). The negative input can be fed either from an external input pin (AINx) or from one of the

several internal reference voltage sources common to all comparators. The user selects the input source

as follows:

• The positive input is selected by the Positive Input MUX Select bit group in the Comparator Control

• The negative input is selected by the Negative Input MUX Select bit group in the Comparator Control

In the case of using an external I/O pin, the selected pin must be configured for analog use in the PORT

Controller by disabling the digital input and output. The switching of the analog input multiplexers is

controlled to minimize crosstalk between the channels. The input selection must be changed only while

the individual comparator is disabled.

Note: For internal use of the comparison results by the CCL, this bit must be 0x1 or 0x2.

46.6.4 Window Operation

Each comparator pair can be configured to work together in Window mode. In this mode, a voltage range

is defined, and the comparators give information about whether an input signal is within this range or not.

Window mode is enabled by the Window Enable x bit in the Window Control register (WINCTRL.WENx).

Both comparators in a pair must have the same measurement mode setting in their respective

Comparator Control Registers (COMPCTRLx.SINGLE).

To physically configure the pair of comparators for Window mode, the same I/O pin must be chosen as

positive input for each comparator, providing a shared input signal. The negative inputs define the range

for the window. In Figure 46-4, COMP0 defines the upper limit and COMP1 defines the lower limit of the

window, as shown but the window will also work in the opposite configuration with COMP0 lower and

COMP1 higher. The current state of the window function is available in the Window x State bit group of

the Status register (STATUS.WSTATEx).

Window mode can be configured to generate interrupts when the input voltage changes to below the

window, when the input voltage changes to above the window, when the input voltage changes into the

window or when the input voltage changes outside the window. The interrupt selections are set by the

Window Interrupt Selection bit field in the Window Control register (WINCTRL.WINTSEL). Events are

generated using the inside/outside state of the window, regardless of whether the interrupt is enabled or

not. Note that the individual comparator outputs, interrupts and events continue to function normally

during Window mode.

SAM D5x/E5x Family Data Sheet

AC – Analog Comparators

Datasheet

DS60001507E-page 1646