Application examples

AN4232

14/17

DocID024134 Rev 2

Here is how the peripherals used are configured:

1.

COMP4 is configured as follows:

a)

The inverting input is connected to DAC1

b)

The non inverting input is connected to the Humidity sensor

c)

The output is connected internally to TIM4 channel 2 (configured in input capture

mode).

2.

TIM4 is clocked at 72 MHz and TIM4 channel 2 is configured in input capture mode to

measure the time constant.

3.

TIM3 is clocked at 72 MHz channel 3 and configured in PWM mode with the duty cycle

at 50%.

4.

DAC1 is used to set the threshold (reference) and it is equal to 2.85V. It is internally

connected to COMP4 inverting input.

Figure 8 shows the block diagram of the application and how the peripherals used are inter-

connected.

Figure 8. Block diagram of the humidity measurement application