I try to design a moisture sensor for the Raspberry Pi. To get a more stable measurement my idea was to use the 555 to generate a frequency depending on the capacitance. The circuit looks as follows:
I'm new to electronics, and I'm a bit worried since the circuit uses 5 V and the Raspberry Pi only handles 3.3 V. I've therefor added this voltage divider in the lower left corner for the output JP1 Pin2 which should transform the voltage of the output pin to a max of 3.3 V.
Is this enough or do I have to take other measures to translate the voltages?