AGX Xavier GPIO pins keep at zero

Autonomous Machines Jetson & Embedded Systems Jetson AGX Xavier
1

We need 10 GPIO pins of AGX and are trying to verify J30 GPIO expansion header pins.
As we measured the signal with multimeter, we found more than 10 pins gpio did not act as we expect.
Only severl pins acted as we expected.
The pins below always kept at 0 as we set GPIO pin to output and set value to 1.
pin11 (uart1_RTS), pin13(pwm01), pin15 (GPIO27_PWM2), pin19,pin 21(SPI1_MISO)(GPIO# 492),23,35…

However pin29 CAN0_DIN, pin31, pin33 worked as the value we set.

Below is the way I tested, did I miss any?
Or those pins can not be set to GPIO?

an example : pin 21(SPI1_MISO)(GPIO# 492)
root@jetson-0423318034979:/sys/class/gpio# echo 492 > export
root@jetson-0423318034979:/sys/class/gpio# cd gpio492
root@jetson-0423318034979:/sys/class/gpio/gpio492# echo out > direction
root@jetson-0423318034979:/sys/class/gpio/gpio492# echo 1 > value
root@jetson-0423318034979:/sys/class/gpio/gpio492# cat value
1 ----- multimeter showed 0
root@jetson-0423318034979:/sys/class/gpio/gpio492# cat direction
out
root@jetson-0423318034979:/sys/class/gpio/gpio492# echo 0 > value
root@jetson-0423318034979:/sys/class/gpio/gpio492# cat value
0

agx_j30_expansion_header_noact.png

2

hello HuiW,

you should customize the pinmux spreadsheet and update the board with the cfg files for GPIO usage.
suggest you check the documentation, Pinmux and GPIO Configuration for the steps,
you may also access pinmux spreadsheets via Jetson Download Center,
you’ll need to re-flash the board with the new cfg files to make the change.
thanks

3

Hi JerryChang,

Thank you for your support.
We did follow the documentations to adjust GPIO usage.
We also found the GPIO setting of different L4T versions are different.
However, the new L4T setting does meet our requirement.

Is there a way to know pinmux spreadsheet match which L4T version?
Or pinmux spreadsheet from download center is always for newest L4T?

Thank you,

4

hello HuiW,

in theory, pinmux spreadsheet from download center is for the latest L4T release.
there’re different pinmux spreadsheets and they’re public for each Tegra family, we might found the issue and update its revisions.
thanks