Jetson Xavier GPIO

I have a question about GPIO of Jetson Xavier.
I wanted to make a Python program like “when an input is detected on 15pin, another process runs,” but the problems below occurred.

  1. Once voltage is applied, voltage remains high.
  2. A small noise like touching by a finger applies voltage, and a Python program detects it as an input.

Could you tell me these are specification defects or Xavier’s defects which I used by chance? And are similar cases reported?

hello keisuke_fujita,

may I know which pin you’re used for testing?
for example, https://www.jetsonhacks.com/nvidia-jetson-agx-xavier-gpio-header-pinout/, is it GPIO27_PWM2 you’re working with?
thanks

I tried all “IN” pins and “BI” pins in page 14, P2822_B02_Concept_schematics.pdf( http://developer.nvidia.com/embedded/dlc/jetson-xavier-developer-kit-carrier-board-design-files).

You need a pulldown resistor on the pin for it to go low after voltage is disconnected. CMOS inputs (MOSFET gates) are capacitors, and stay “on” if they aren’t explicitly discharged.

I think there is a pull down register but its size is 1M and it is too large. I think 1K or so is appropriate.

1K would pull 3.3 mA from a 3.3V GPIO, which seems excessive. 10K should be safe and overkill, though, and 47k should be quite sufficient.