GPIO 417 drive strength configuration

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
1

Using the Xavier Dev Kit. Seeing ringing on the output of GPIO 417 (pin 22 on 40 pin header) when output is enabled and driving a 4kohm resistor to ground. I believe the output should be capable of driving 825uA (3.3V/4kohm), so would like to examine what the drive strength is configured to. I have found in documentation there should be a 5 bit configuration to set drive strength. Where are the details on the register address / data to check the configuration of drive strength? How should a new configuration be applied from user space?

2

hello notAnotherUsernameInUse,

  1. please download Jetson AGX Xavier Pinmux to configure the drive strength.
  2. or, you could have modification in sensor device tree.
    for example,
cam1_mclk_ps0 {
                        ...
                        nvidia,pull-down-strength = <0xa>;
                        nvidia,pull-up-strength = <0xa>;
                    };
3

In Jetson AGX Xavier Pinmux document I do not see a configuration for drive strength. Which column in the spreadsheet should be used to configure drive strength?

For clarity, I have attached a picture.
[url]http://www.mosaic-industries.com/embedded-systems/_media/microcontroller-projects/raspberry-pi/raspberry-pi-circuit-gpio-input-pins.png[/url]

In the spreadsheet I think column AB corresponds to pull-up and pull-down in the picture which would be used for an input. For an output the pull-up and pull-down would be disabled. I wish to change “output strength” from the picture. How is this accomplished using the spreadsheet?

For modifying the sensor tree directly, where can the definition of bits be found? In other words, what does 0xA mean? If drive strength were to be increased, does the number go up or down and which bits are used to be changed?

4

This is still a topic which is not understood. If drive strength details are unable to be answered, what are the recommended steps for troubleshooting the oscillation when a 4kohm resistor is connected?

5

hello notAnotherUsernameInUse,

pinmux spreadsheet is able to customize the pin, you should also configure the settings in device tree.
you may also refer to GPIO controller definition.
for example,
$TOP/kernel_src/hardware/nvidia/platform/t19x/galen/kernel-dts/common/tegra194-p2888-0000-a00.dtsi