GPIO pins 2 - 8 work great but 9 and up not

[bengoevaerts]

I wonder what I'm missing with the following issue:
I'm testing all pins to connect multiple push buttons to the PI. My code is working great for pins GPIO2 till GPIO8 but starting from pin GPIO9 (and all pins following), line.getValue() randomly seems to return 0 and 1.

In Python reading (for example) pin 9 is working as expected.
I'm on a Raspberry PI 5 and using global.chip = new Chip(4);

Any help or direction is appreciated. Thanks.

[bengoevaerts]

After some research I guess my question is how to enable pull-up direction (pi's internal resistors) for pins 9 and up. I would assume that line.requestInputMode(); enables this by default.

[noctarius]

For stability, I'd recommend using external pull-up resistors. Internal pull-ups might not be strong enough for stable operation.

In any case, it seems like on a Raspi, only the first 8 pull-ups are enabled by default on bootup. The other ones need to be enabled manually. Not sure if this is still true, as the answer is from 2018: https://forums.raspberrypi.com/viewtopic.php?t=202568#p1259134

When a Pi is first powered up, the first eight GPIOs have pull-ups enabled, and the rest have pull-downs enabled. After it has finished booting, you can change that if you wish, in your software.

[bengoevaerts]

Thanks for the quick reply. The blog post does not mention how to enable pull-up mode. Based on your comment I assume it's not possible using the node-libgpiod library which would be useful!

[sombriks]

hi everyone!

can someone test release 0.5 ? it is supposed to offer a way to configure bias, but i lack the hardware to do so at the moment.