Loopback testing using GPIO pins and Setting pull up and pull down for inputs on GPIO

[ankithsingh]

Hello Nvidia Team,

I need help in 2 of the queries.

1. I want to enable gpio pins on my jetson nano and perform loopback testing after enabling,
   where I want to set one pin as input and one as output. And perform a loopback test in a way where I can try to tweak on what input I want to receive on the pins.
2. I want to use pull up and pull down resistors in order to change the inputs as per the requirement on jetson nano.

Please guide on the above 2 queries or an alternative on how to work on the loopback testing and also to set the pull up and pull down resistors on jetson nano

Thank you

[JerryChang]

hello ankithsingh,

please download pinmux spreadsheets to review the pin configurations,
Nano series is using device tree to configure the pin, you may modify the *.dtsi to modify the pin settings.
please also check Pinmux Changes session as see-also,
thanks

[ankithsingh]

Hello @JerryChang

Thanks for the response

Can you please let me know how to perform loopback testing on nano dev kit and as well to work on the pull up and pull down resistors.

To enable gpio and perform loopback testing do we need to change the pinmux configuration?

Thank you

[linuxdev]

If a pin is not the correct setting for in/out, or it isn’t even running as GPIO, then GPIO for that pin won’t work at all. You do have to set up the PINMUX unless it happens that the default is already the setup you want. There is no avoiding that. I couldn’t say if a pull-up/down is needed, but loopback has no requirements other than connecting an “in” pin to an “out” pin. The trouble is you can’t just connect random pins (which is what the PINMUX is designed to set up to work correctly with even after a reboot).