macOS HomeKit automation

The problem

My Mac mini is hooked up to a pair of Yamaha HS8s via a TASCAM 208i. The manual instructs you to turn the speakers off when not in use to prevent wear. Fishing for the power switch behind each speaker got annoying quickly, so I decided to automate the process.

The solution

Since I can't control the speakers remotely, I opted to leave them on and control the power socket instead. I bought a Wemo HomeKit smart plug, connected the speakers to it, and then added it to the Home app. Sure enough, when I toggle the smart plug, everything springs to life.

Next, I created a pair of shortcuts via the Shortcuts app to power the speakers on and off.

Since macOS ships a Shortcuts command line utility, we can now control the speakers like so:

shortcuts run 'Turn speakers on'
shortcuts run 'Turn speakers off'

The last puzzle piece is running the appropriate shortcut upon sleeping and waking. I opted to use Hammerspoon since it lets us conveniently hook into macOS events via Lua scripts.

The caffeinate.watcher module contains the functionality we're after. After creating and starting a caffeinate watcher, it'll run your callback function in response to power events. Since I'm only interested in sleep and wake events, I filtered the rest out.

Here's an example ~/.hammerspoon/init.lua:

local watcher = hs.caffeinate.watcher

local function power_callback(event)
    if event == watcher.systemDidWake then
        os.execute("shortcuts run 'Turn speakers on'")
    elseif event == watcher.systemWillSleep then
        os.execute("shortcuts run 'Turn speakers off'")
    end
end

watcher.new(power_callback):start()

Finally, reload the Hammerspoon config and attempt to justify how much time you spent automating a ten-second task.