I/O Expander - TCA9539 - configuring with device tree

Robotics & Edge Computing Jetson & Embedded Systems Jetson TX2
1

Hi,
I’m trying to set the defaults for the GPIO pins controlled by the TCA9539 GPIO expander on the Jetson.

Where should the device tree be modified?
How to manipulate these I/O’s from a running system?

The standard “echo > export” method fails with “device or resource busy”, probably because the expander driver controls these pins.

Thanks.

2

hello Mike_0b,

the device Jetson TX2 used is tegra186-quill-p3310-1000-c03-00-base.dtb,
it is composite with several module device trees.
you’re able to find them under below path. thanks

r28.1_sources/hardware/nvidia/platform/t18x/
3

Hi JerryChang,

Thanks,
I am aware of the location of the DTS file, I was asking more about the exact property value for these pins, but I think I got it already:

In

tegra186-cvb-prod-p2597-b00-p3310-1000-a00-00.dtsi

, I modified the

gpio@74

property (for the expander at I2C address 0x74).

However, I’m still not sure how to toggle the pins from a running system.

4

hello Mike_0b,

could you please refer to below similar topic,
thanks

[url]GPIO Pinmux - Jetson TX2 - NVIDIA Developer Forums