Build a Binary Clock with Elixir and Nerves

Build the Service Layer

Adapters are boundary layers that run on a specified target to control hardware and also in host environments for convenience. With the adapters in hand, the clock is almost complete. It can translate an Elixir time to LEDs upon request. The last problem is making that request at one-second intervals.

Recall that the adapters already send one second :tick messages. The new service layer needs only respond to them.

Build the Service

This GenServer in lib/clock/server.ex will be short and sweet. It will need to keep an adapter, a time zone, and the local time, like this:

defmodule Clock.Server do
  defstruct [:adapter, :time, :timezone]
  use GenServer
  @spi_bus_name "spidev0.0"
  @timezone "US/Eastern" ...