Comparator - ST STM32L152-EVAL User Manual

UM1018
2.13
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Comparator

3 I/Os are used to implement a comparator feature as shown in
● Comparator non-inverting input PB4 connected to LDR (R34).
● Comparator inverting input PB3 connected to potentiometer (RV3) used as variable
threshold input for comparison to luminosity measured on LDR.
●
Comparator non-inverting input PB5 connected to potentiometer (RV3) used as
analogue voltage input for comparison with internal voltage reference (for instance
Band gap) in order to test analogue Wakeup feature of the MCU.
Figure 3. STM32L152-EVAL comparator features
Jumper JP17 allows 3 different usages of the potentiometer as shown in
Table 10. Comparator and potentiometer related jumpers
Jumper
Potentiometer RV3 is connected to ADC input PB12. Used as ADC input
when JP17 is set as shown (default setting).
Potentiometer RV3 used as LDR variable threshold. Input is connected to
JP17
comparator inverting input GPCOMP_IN- (PB3) when JP17 is set as shown.
Potentiometer RV3 is connected to non-inverting input GPCOMP_IN+(PB5).
The comparator inverting input can be connected to ¼ band gap, ½ band
gap, band gap or DAC internally in order to test the possibility to wakeup the
MCU when an external voltage reaches a programmable threshold when
JP17 is set as shown.
Description
Doc ID 18141 Rev 1
Hardware and layout
Figure 3.
Table 10.
Setting
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