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Python utilities for NVIDIA Jetson

Jetson Control Utility

The purpose of this utility is to let users control NVIDIA Jetson boards for automation. It talks to the Jetson boards via an FTDI chip integrated on some developer kit baseboards. Refer to developer kit documentation to determine if your developer kit or baseboard supports this feature.

This utility has been validated on the following platforms:

  • Jetson AGX Xavier

Dependencies

The Jetson control utility is written for Python 3 and doesn't implement backwards compatibility with Python 2. It primarily relies on the Python standard library, but uses the pyftdi library to communicate with FTDI chips. You can obtain pyftdi from Pypi or Github.

Most distributions don't provide a package for pyftdi, unfortunately, so you'll have to manually install it using pip:

$ pip install pyftdi

Alternatively, use your preferred method to install pyftdi. Note that pyftdi is known to occasionally break API compatibility with earlier versions. The version that this tool was written against is pyftdi v0.52.9.

Usage

jetson-control will use the first available FTDI chip that can be found. There is also a mechanism to pick a specific instance identified by its serial number.

Each invocation of jetson-control executes a single command, which makes it well suited for scripting.

Commands

To find out which devices exist on a system run the devices command. It lists all the compatible devices found on the USB bus.

Buttons can be controlled using the press and release commands, each of which take the name of the button to control as a parameter.

The following buttons are defined:

  • power: press to power up the device, press and hold for 10 seconds to force power off
  • reset: pressing this button puts the device into reset, release to boot
  • recovery: must be pressed before the reset button is released or when the power button is pressed in order to enter recovery mode
  • force-off: forces the device off immediately

The utility supports reading, writing and erasing the EEPROM using the eeprom command. Several sub-commands are available, such as read to save the EEPROM contents into a file, specified as an argument, write to flash the contents of a file, specified as an argument, or erase to erase the EEPROM. The dump and show commands can be used to read the EEPROM and show a hexdump or a decoded version, respectively.

Some boards support querying the state of the core and the CPU power rails. This can be done using the power-rail command. An optional argument can be used to specify the name of the rail to query. If no value is specified, the status for all power rails will be shown.

Tegra Combined UART Demuxer

The Tegra Combined UART is used on Jetson AGX Xavier and platforms based on the Xavier SoC to multiplex the log output of several producers on the SoC (CCPLEX, BPMP, ...). While it is possible to capture the entirety of the log output from the UART with a terminal emulator, doing so can make the output unreadable.

The jetson-demux utility creates pseudo terminal master/slave pairs for each of the streams multiplexed onto a given UART. The content of each stream is then sent to the corresponding PTY, which can be connected to using your favorite terminal emulator. Input from the PTY is transmitted back via the TCU, allowing bi-directional communication.

Launch the demuxer by running:

$ jetson-demux --device /dev/ttyUSBX

Where /dev/ttyUSBX corresponds to the UART that receives the multiplexed streams from the TCU. This command will show a list of PTYs that have been created, one for each of the TCU streams. Connect to the stream of interest by passing the path to the PTY to your favorite terminal emulator.