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Nerves can use the serial number programmed into the NervesKey for the hostname. This can come in handy for finding devices on the network since the hostname can be reported via DHCP or broadcast using mDNS.
The DHCP client for Nerves reports hostnames to the DHCP server. Some DHCP servers like dnsmasq-based ones register those names with a colocated DNS server so that requests of that name return the IP address of the Nerves-based device. Many DHCP servers do not do this, so mDNS is the only option for easily finding the device.
In Nerves, the
boardidprogram reads serial numbers off of boards. It has options to support many different kinds of hardware. To have it read the serial number off the NervesKey, add a
rootfs_overlay/etc/boardid.conffile to your Nerves project. This will override the
boardid.confdistributed with your Nerves system (assuming that you're using an official Nerves system). The contents should be:
-b nerves_key -f /dev/i2c-1
If your NervesKey is attached via a different I2C bus, update the
If this doesn't work, you can test
boardidat the IEx prompt using the Toolshed
System.cmd/3if not using Toolshed) by running:
iex> cmd("boardid -b nerves_key -f /dev/i2c-1 -b force -f failed")
-b force -f failedpart ensures that
boardiddoesn't fall back to try to find a serial number based on options in a
boardid --helpfor more information.