GPIO Wakeup Pin Configuration Issue

Robotics & Edge Computing Jetson & Embedded Systems Jetson Nano
1

Hello,

  • Jetson Nano with Jetpack 4.6.1

I am having an issue with configuring GPIO pins within the device tree. The sources that I have been reading off of are:

  1. Jetson/Device Tree - eLinux.org
  2. Jetson/FAQ/BSP/Nano Wakeup Pin - eLinux.org

So far I have run the following commands:

sudo apt update
sudo apt install device-tree-compiler
cd /boot
dtc -I dtb -O dts -o output.dts tegra210-p3448-0002-p3449-0000-b00.dtb
gedit output.dts

My gpio-keys node within output.dts looks like this. I added the wakeup_key part as per source #2 (eLinux Nano Wakeup Pin).

gpio-keys {
		compatible = "gpio-keys";
		gpio-keys,name = "gpio-keys";
		status = "okay";
		disable-on-recovery-kernel;

		power {
			label = "Power";
			gpios = <0x5b 0xbd 0x1>;
			linux,code = <0x74>;
			gpio-key,wakeup;
			debounce-interval = <0x1e>;
			nvidia,pmc-wakeup = <0x3c 0x0 0x18 0x0>;
		};

		forcerecovery {
			label = "Forcerecovery";
			gpios = <0x5b 0xbe 0x1>;
			linux,code = <0x74>;
			gpio-key,wakeup;
			debounce-interval = <0x1e>;
		};

		wakeup_key {
			label = "WakeupKey";
			gpios = <&gpio TEGRA_GPIO(G, 3) GPIO_ACTIVE_LOW>;
			linux,code = <KEY_POWER>;
			gpio-key,wakeup;
			debounce-interval = <30>;
			nvidia,pmc-wakeup = <&tegra_pmc
			    PMC_WAKE_TYPE_GPIO 6 PMC_TRIGGER_TYPE_NONE>;
		};

	};

When I run the following command to compile output.dts, I get a syntax error.

dtc -I dts -O dtb -o tegra210-p3448-0002-p3449-0000-b00.dtb output.dts 
Error: output.dts:7698.23-24 syntax error
FATAL ERROR: Unable to parse input tree

My guess is that the gpios, debounce interval, and nvidia,pmc-wakeup need to be in hex, but I don’t know where to find the codes for those.

Also within source #2 from above, I have not been able to figure out how to do the “Set Pinmux” step of configuring the GPIO pins.

Any help is greatly appreciated!

3

Hi roak1317,

Are you using the devkit or custom board for Jetson Nano?

Correct. You could refer to the value from other nodes to get the hex, or you could just download the kernel source and modify the device tree.

4

I am using the devkit.
I’m not sure how I would refer to the value from other nodes to get the hex.
Where could I download the kernel source and modify the device tree?

5

Please refer to the following instruction.
NVIDIA Jetson Linux Developer Guide : Kernel Customization | NVIDIA Docs

6

Is there a better way to configure a pin to be a wakeup pin? This was my original post for context: Enabling Wake-Up from Deep Sleep on Jetson Nano with LIDAR Sensor

7

You should always configure the device tree for any use case including set it for wake-up.
Please just refer to the porting guide from your vendor and modify them from source.

9

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