I am trying to work out what resistor to use in a circuit.
The circuit is a series circuit. The power to the circuit is 5.5V, with a switch, which connects to a GPIO pin on the RasberryPi. I believe 3.3V is needed for the pull up resistor on the RPi.
I need to use a resistor to lower the power from 5.5V to 3.3V. I know Ohms law, but I'm struggling to use it in practice. How can I figure out the required resistor needed for this situation, and for future knowledge?
Is their a formula I can note down?