A RC filter and a NTC temperature sensor are connected to ADC0 and ADC1 respectively. These analog sensors are used as input to the ADC but it is also possible to disconnect them by cutting the cut-straps on the bottom side of the board.
The RC filter (1. order low-pass) has an approximate 3dB cut-off frequency of 159 Hz. The input to the RC filter is one of the UC3 GPIO pins that can be configured to output a PWM signal to the RC filter. This can be used to generate a DC voltage on the output of the RC filter which can be measured on the ADC. As this is a 1.order filter, the ripple on the DC voltage is inversly proportional to the input frequency. A higher input frequency will give lower ripple on the output.