Abnormal GPIO voltage with 3.3V pull-up for a button

Robotics & Edge Computing Jetson Systems Jetson Thor
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1

Hi NVIDIA team,
I am currently working on a custom carrier board. We are using the following pins for the switch:

  • spi1_cs1_pk3
  • soc_gpio128_pl4
  • dap6_sclk_pp2
  • dap6_din_pp4
  • dap6_fs_pp5

Initially, we routed these pins through a TXB0108 level shifter with external 3.3V pull-ups for the buttons, but we observed an abnormal ~1V level. We suspect this is a hardware conflict between the TXB series and the external pull-up resistor for open-drain applications.

Before we modify our hardware design to bypass the level shifter, we want to verify the specific capabilities of these pins to ensure we are on the right track.

Question: Can all of these specific pins be safely configured and used as standard GPIO inputs for push buttons? Are there any hardware or pinmux restrictions we should be aware of?

Thanks!

3

The pins you listed are all 1.8V I/O and can be used as open drain inputs for push buttons as long as the pull ups on the module side are to 1.8V.

The E_IO_OD entry in the pinmux to enable open drain on Jetson Thor does NOT support 3.3V I/O as on previous Jetsons. In general, the signals connecting to Jetson Thor MUST be 1.8V. The only pins supporting 3.3V are labeled as such in the pinmux spreadsheet and/or on the Thor module board to board (B2B) schematic symbol provided by NVIDIA.