Window Comparator

The ADC can raise the Window Comparator Interrupt (WCMP) flag in the Interrupt Flags (ADCn.INTFLAGS) register and request an interrupt (WCMP) when the output of a conversion or accumulation is above and/or below certain thresholds. The available modes are:

The value is above a threshold
The value is below a threshold
The value is inside a window (above the lower threshold and below the upper threshold)
The value is outside a window (either below the lower threshold or above the upper threshold)

The thresholds are set by writing to the Window Comparator Low and High Threshold (ADCn.WINLT and ADCn.WINHT) registers. The Window mode to use is selected by the Window Comparator mode (WINCM) bit field in the Control D (ADCn.CTRLD) register.

The Window Mode Source (WINSRC) bit in the Control D (ADCn.CTRLD) register selects if the comparison is done on the 16 LSb of the Result (ADCn.RESULT) register or the Sample (ADCn.SAMPLE) register. If an interrupt request is enabled for the WCMP flag, WINSRC selects which interrupt vector to request, RESRDY or SAMPRDY.

When accumulating multiple samples, if the Window Comparator source is the Result register, the comparison between the result and the threshold(s) will happen after the last conversion is complete. If the source is the Sample register, the comparison will happen after every conversion.

Assuming the ADC is already configured to run, follow these steps to use the Window Comparator mode:

1.Set the required threshold(s) by writing to the Window Comparator Low and High Threshold (ADCn.WINLT and ADCn.WINHT) registers.
2.Optional: Enable the interrupt request by writing a ‘1’ to the Window Comparator Interrupt Enable (WCMP) bit in the Interrupt Control (ADCn.INTCTRL) register.
3.Enable the Window Comparator by writing the WINSRC bit field and a non-zero value to the WINCM bit field in the Control D (ADCn.CTRLD) register.

ATtiny1624/1626/1627

Window Comparator