Arduino uno realizes simple touch switch through direct detection of capacitance

Arduino The simple touch switch is realized through the direct detection of capacitance

Arduino In addition to receiving digital signals from digital ports , The only analog physical quantity that can be detected is voltage . The detection value of any analog sensor is almost converted into voltage value through relevant circuit , Then input its analog port for analog-to-digital conversion . Capacitance values require relatively more complex and expensive circuits to be converted into voltage values , Can be Arduino testing , And the detection of many physical processes , Can be easily and reliably realized by detecting the capacitance value .

Implementation method

Set a digital port to low potential , And open arduino The internal pull-up resistance of , Start to calculate the time required for this port to reach the high potential . And this time is related to the ground capacitance of this port , The greater the capacitance , The longer the time . On the hardware, you only need to connect a wire to one port . Touch the exposed end of this wire with your finger , Will cause capacitance change ,arduino This change can be detected by the above method . If you want to increase sensitivity , You can attach a piece of tin foil to the wire . To prevent you from having a strong static electric shock to puncture the chip , You can cover the tin foil with a thin layer of paper .

Sample code

No need for third-party libraries

// readCapacitivePin
// Input :Arduino pin number