상황
A TTP223 capacitive touch module is powered from the Raspberry Pi 3.3V rail, and its active-high output drives a GPIO pin through a series resistor while a pulldown resistor keeps the pin low when untouched.
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01
Use the Raspberry Pi 3.3V header supply to stay within GPIO voltage tolerance.
02
Add a 100k pulldown on the GPIO input so the pin reads low when the touch pad is idle.
03
Use a 1k series resistor to protect the GPIO pin from transient output conditions.
Reusable for any 3.3V MCU GPIO when wiring a TTP223 active-high touch switch module with a local bypass capacitor and output conditioning.