NervesGrisp

A Nerves application configured to run on GRiSP2 hardware and connect to NervesHub for over-the-air firmware updates via nerves_hub_link.

Requirements

• Elixir and Mix installed
• MIX_TARGET=grisp2 environment variable for hardware builds
• SSH public key in ~/.ssh/ for device access
  • NOTE: If you have multiple SSH keys, your client will try them in order and stop after 4 attempts — the device will reject the connection if the right key isn't among the first four tried. To avoid this, either explicitly specify the key with -i ~/.ssh/your_key or configure your ~/.ssh/config to use the correct key for the device's IP/hostname:

Host 192.168.1.*
  IdentityFile ~/.ssh/id_rsa
  IdentitiesOnly yes

• GRiSP2 board (for hardware deployment)

Getting Started

Install dependencies and build firmware:

mix deps.get
MIX_TARGET=grisp2 mix firmware

Flashing

First Flash

For the initial flash, follow the GRiSP2 boot notes to prepare your SD card, then build and upload:

MIX_TARGET=grisp2 mix firmware
MIX_TARGET=grisp2 mix upload <device-ip-or-hostname>

Example:

MIX_TARGET=grisp2 mix upload 192.168.1.231
# or using hostname:
MIX_TARGET=grisp2 mix upload my-grisp2.local

Subsequent Updates

Once the device is running and connected to the network, you can push OTA updates directly through NervesHub or via SSH upload.

Local Configuration & Secrets

Sensitive configuration (WiFi credentials, SSH keys, NervesHub certs, etc.) should never be committed to version control. Instead, use local override files that are gitignored:

File	Purpose
config/grisp2.override.exs	Overrides for GRiSP2 hardware target
config/local.override.exs	Overrides for running locally (host target)

These files are loaded at the end of the respective target config and take precedence over defaults.

grisp2.override.exs — Full Example

import Config

keys =
  System.user_home!()
  |> Path.join(".ssh/id_ras.pub")
  |> Path.wildcard()

if keys == [],
  do:
    Mix.raise("""
    No SSH public keys found in ~/.ssh. An ssh authorized key is needed to
    log into the Nerves device and update firmware on it using ssh.
    See your project's config.exs for this error message.
    """)

config :nerves_ssh,
  authorized_keys: Enum.map(keys, &File.read!/1)

config :vintage_net,
  regulatory_domain: "00",
  config: [
    {"usb0", %{type: VintageNetDirect}},
    {"eth0",
     %{
       type: VintageNetEthernet,
       ipv4: %{method: :dhcp}
     }},
    {"wlan0",
     %{
       type: VintageNetWiFi,
       vintage_net_wifi: %{
         networks: [
           %{
             key_mgmt: :wpa_psk,
             ssid: "YOUR_SSID",       # <-- replace with your WiFi SSID
             psk: "YOUR_PASSWORD"     # <-- replace with your WiFi password
           }
         ]
       },
       ipv4: %{method: :dhcp}
     }}
  ]

# Nerves Hun Link configuration
config :nerves_hub_link,
  client: Gateway.Firmware.NervesHub,
  host: "your-nerves-hub-host:4300",  # <-- replace with your NervesHub host/port
  remote_iex: true,
  connect: true,
  connect_wait_for_network: false,
  configurator: NervesHubLink.Configurator.LocalCertKey,
  ssl: [
    certfile: "/etc/bridge-001.cert.pem",
    keyfile: "/etc/bridge-001.key.pem"
  ]

local.override.exs — Example

Used when running the app on your development machine (host target). Typically you only need to override things that differ from the hardware config, such as disabling hardware-specific interfaces.

import Config

# Example: no network config needed for host target
# config :vintage_net, config: []

NervesHub OTA Updates

This project uses nerves_hub_link to receive firmware updates from a NervesHub server. Make sure the device certificate and key are provisioned on the device before connecting.

Key configuration options (set in grisp2.override.exs):

Option	Description
host	NervesHub server hostname and port
remote_iex	Enables remote IEx shell via NervesHub
connect	Auto-connect to NervesHub on boot
ssl.certfile	Path to device certificate on the filesystem
ssl.keyfile	Path to device private key on the filesystem

Useful Links

• Nerves Project
• GRiSP2 Nerves System
• NervesHub
• nerves_hub_link
• VintageNet