6.3 Observe ADC Functionality and Current
Consumption in Data Visualizer
Open Data Visualizer by clicking the Data Visualizer tab to observe
the ADC functionality and look at the power consumption, as shown in Figure 6-5.Figure 6-5. ADC Data Print to USART Terminal and
Power Analysis for ADC WCMP Mode
By rotating the potentiometer knob, the voltage input to ADC input pin, PB1, is
changing. The ADC result is printed to the terminal only when it is below 80, which is the ADC
window low threshold value. When the value is above that, ADC WCMP interrupt will not be
triggered and hence no data will be printed to the terminal.
In the power analysis window, when looking at the current consumption, the
average current consumption is about 1.18 μA which is slightly reduced from 1.32 μA in the
previous assignment. This is because the ADC WCMP mode is now used. There are now two
categories of the high peak glitches:
When the RTC overflow interrupt triggers
to start the ADC conversion while the ADC result is above the ADC window low threshold
value and the USART transmission is NOT performed. This is illustrated in the first half
of the power analysis graph, with a current consumption around 240 μA. This has been
reduced from constant 690 μA in the previous assignment at where no window filter feature
is available.
When the RTC overflow interrupt triggers
to start the ADC conversion while the ADC result is below the ADC window low threshold
value and the USART transmission is performed. This is illustrated in the second half of
the power analysis graph, with a current consumption around 690 μA. This is equivalent to
the peak glitches in the previous assignment.
As shown, this application with implementing the ADC WCMP mode can reduce the peak
current consumption, when the ADC result is out of interest and no USART transmission, is
triggered.
Result: The ADC
WCMP mode slightly reduces the average current consumption. It mainly reduces the current
consumption for the scenario when the ADC result is above the window threshold value and no
USART transmission triggers. The benefit varies depending on how often this scenario happens.
Note that there are four different window compare modes available to fit the user's
requirement.
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