PWM8 not working on JetsonXavierNX (GPIO07/pin32)

[BasGAus]

Hi,

Working on a custom board (Jetson Xavier NX - Jetpack 4.5), not a devKit, I would like to use the PWM capability of the GPIO07 (gpio424 on my board). But it doesn’t work.

I used the jetson-io.py tool, as it is explained in the documentation, to configure the pin as needed but nothing changed. After a complete reboot of the board, the configuration that I changed on pin32 vanished and the pin still get the status “unused”.

I used the following commands to generate a 10Hz signal, which is working on another board with the same parameters/env :

$ echo 0 > /sys/class/pwm/pwmchip4/unexport
$ echo 1 > /sys/class/pwm/pwmchip4/export
$ echo "0" > /sys/class/pwm/pwmchip4/pwm0/enable
$ echo "100000000" > /sys/class/pwm/pwmchip4/pwm0/period
$ echo "50000000" > /sys/class/pwm/pwmchip4/pwm0/duty_cycle
$ echo "1" > /sys/class/pwm/pwmchip4/pwm0/enable

In this case, the commands are inefficient.
But, I’m able to control the GPIO07 with (Low/High) :

$ echo 424 > /sys/class/gpio/export
$ echo 0 > /sys/class/gpio/gpio424/value
$ echo 1 > /sys/class/gpio/gpio424/value
$ echo 0 > /sys/class/gpio/gpio424/value

I don’t understand why I’m able to change the state of the pin but not use it as a PWM ?
If you need more info, please ask me ;)

Thank you in advance.

[JerryChang]

hello BasGAus,

since you’re using a customer board, you’ll need to use the pinmux spreadsheets to modify the pin configurations.
please access pinmux spreadsheets for reference, thanks

[BasGAus]

Hi,

Thanks for the reply.
We have not changed any of the hardware configuration. So the pinmux is the same.

I send you the DeviceTree configuration (.dtb) that was saved after using the jetson-io.py tool. You will see that the configuration for pin32 hasn’t changed, despite the use of the tool. (used with sudo and “save and reboot” option)

configPin32_Carte11.txt (387.4 KB)
File saved just after the modification of pin32(pwm8).

Do you have any idea about why it is still configured to “unused”/gp after using the dedicated tool ?

Thank you for your time

[JerryChang]

hello BasGAus,

as you can see in the default pin settings, GPIO07 is configured as GPIO, GPIO3_PR.00 by default;
please use the pinmux spreadsheets to modify the pin configurations to set it as SFIO, GP_PWM8.
for your reference, here’s created *.dtsi file with SFIO settings.

		pinmux_default: common {
			/* SFIO Pin Configuration */
...
			soc_gpio44_pr0 {
				nvidia,pins = "soc_gpio44_pr0";
				nvidia,function = "gp";
				nvidia,pull = <TEGRA_PIN_PULL_DOWN>;
				nvidia,tristate = <TEGRA_PIN_DISABLE>;
				nvidia,enable-input = <TEGRA_PIN_DISABLE>;
				nvidia,io-high-voltage = <TEGRA_PIN_DISABLE>;
				nvidia,lpdr = <TEGRA_PIN_DISABLE>;
			};