Nerves System Jetson Nano

TODO: Add CICD TODO: Add Hexpm

The base Nerves System configuration for the NVIDIA Jetson Nano developer kit, 4GB SD model (p3450-0000).

Processing
CPU	64-bit Quad-core ARM A57 @ 1.43GHz
GPU	128-core NVIDIA Maxwell @ 921MHz
Memory	4GB 64-bit LPDDR4 @ 1600MHz | 25.6 GB/s
Video Encoder*	4Kp30 | (4x) 1080p30 | (2x) 1080p60
Video Decoder*	4Kp60
------------------------	-----------------------------
Interfaces
------------------------	-----------------------------
USB	4x USB 3.0 A (Host) | USB 2.0 Micro B (Device)
Camera	MIPI CSI-2 x2 (15-position Flex Connector)
Display	HDMI | DisplayPort
Networking	Gigabit Ethernet (RJ45)
Wireless	M.2 Key-E with PCIe x1
Storage	MicroSD Card
Other I/O	(3x) I2C | (2x) SPI | UART | I2S | GPIOs
------------------------	-----------------------------
Other
------------------------	-----------------------------
Linux Kernel	4.9
IEx terminal	TODO

*Indicates maximum number of concurrent streams up to the aggregate throughput. Supported video codecs: H.265, H.264, VP8, VP9 (VP9 decode only)

For more technical specifications, see the Jetson Developer Blog.

Please contact us about this if you're interested in it. This is currently experimental.

Using

The most common way of using this Nerves System is create a project with mix nerves.new and to export MIX_TARGET=jetson_nano. See the Getting started guide for more information.

If you need custom modifications to this system for your device, clone this repository and update as described in Making custom systems

If you're new to Nerves, check out the nerves_init_gadget project for creating a starter project. It will get you started with the basics like bringing up networking, initializing the writable application data partition, and enabling ssh-based firmware updates. It's easiest to begin by using the wired Ethernet interface 'eth0' and DHCP.

Root disk naming - TODO - translate for Nano

If you have multiple SSDs, or other devices connected, it's possible that Linux will enumerate those devices in a nondeterministic order. This can be mitigated by using udev to populate the /dev/disks/by-* directories, but even this can be inconvenient when you just want to refer to the drive that provides the root filesystem. To address this, erlinit creates /dev/rootdisk0, /dev/rootdisk0p1, etc. and symlinks them to the expected devices. For example, if your root file system is on /dev/mmcblk0p1, you'll get a symlink from /dev/rootdisk0p1 to /dev/mmcblk0p1 and the whole disk will be /dev/rootdisk0. Similarly, if the root filesystem is on /dev/sdb1, you'd still get /dev/rootdisk0p1 and /dev/rootdisk0 and they'd by symlinked to /dev/sdb1 and /dev/sdb respectively.

Provisioning devices - TODO - verify still works on Nano

This system supports storing provisioning information in a small key-value store outside of any filesystem. Provisioning is an optional step and reasonable defaults are provided if this is missing.

Provisioning information can be queried using the Nerves.Runtime KV store's Nerves.Runtime.KV.get/1 function.

Keys used by this system are:

Key	Example Value	Description
nerves_serial_number	"12345678"	By default, this string is used to create unique hostnames and Erlang node names. If unset, it defaults to part of the Ethernet adapter's MAC address.

The normal procedure would be to set these keys once in manufacturing or before deployment and then leave them alone.

For example, to provision a serial number on a running device, run the following and reboot:

iex> cmd("fw_setenv nerves_serial_number 12345678")

This system supports setting the serial number offline. To do this, set the NERVES_SERIAL_NUMBER environment variable when burning the firmware. If you're programming MicroSD cards using fwup, the commandline is:

sudo NERVES_SERIAL_NUMBER=12345678 fwup path_to_firmware.fw

Serial numbers are stored on the MicroSD card so if the MicroSD card is replaced, the serial number will need to be reprogrammed. The numbers are stored in a U-boot environment block. This is a special region that is separate from the application partition so reformatting the application partition will not lose the serial number or any other data stored in this block.

Additional key value pairs can be provisioned by overriding the default provisioning.conf file location by setting the environment variable NERVES_PROVISIONING=/path/to/provisioning.conf. The default provisioning.conf will set the nerves_serial_number, if you override the location to this file, you will be responsible for setting this yourself.

Troubleshooting - TODO - accurate for Nano?

Device boots to GRUB CLI

If this happens, something could be off with the grub.cfg. Couple things you should check here:

1. Make sure all your UUID's match what is in your fwup.conf
2. Your boot drive may be off (default uses hd0). Run ls in the grub CLI and you may see something like this:

   grub> ls
   
   (hd0) (hd1,gpt1) (hd1,gpt2) (hd1,gpt3) (hd1,gpt4) (hd2) (hd3) (hd4)

   If you do, you need to change which hd is looked at in grub.cfg, which means copying a few configs from here into your Nerves app:

   $ cp fwup.conf /path/to/my_app/config/
   $ cp grub.cfg /path/to/my_app/config/

   Change the line in your new config/fwup.conf to look at your custom grub.cfg

   file-resource grub.cfg {
       host-path = "${NERVES_APP}/config/grub.cfg"
   }

   Then change your new config/grub.cfg to match the hd needed. Lastly, specify to use the new fwup.conf in your Nerves app config/config.exs

   config :nerves, :firmware, fwup_conf: "config/fwup.conf"

   Rebuild your firmware and try to boot again.

Installation - TODO

If available in Hex, the package can be installed by adding nerves_target_jetson_nano to your list of dependencies in mix.exs:

def deps do
  [
    {:nerves_target_jetson_nano, "~> 0.1.0"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/nerves_target_jetson_nano.