# RPM Inputs ![](/files/-LChAXU8UlgWOkN-HSMl) The RPM connector provides 5V and GND for the hall effect sensors, then takes two signals, one from each sensor. The hall effect sensors act as switches. When no magnet is detected, there is no connection between the signal pin and ground. When a magnet is sensed, the signal pin connects to ground. To turn this into a signal readable by the Arduino, we need to pull the signal line up to 5V when there is no connection, and allow it to drop to 0V when the magnet is sensed. R16 and R17 are pull-up resistors that do this. R18 and R19 are protection resistors to prevent too much current reaching the Arduino in the event of a wiring mistake. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.echook.uk/circuit-schematics/rpm-inputs.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.