Key light shenanigans | Christopher B. Goodman

I bought a Logitech Litra Glow key light for my home office during Amazon’s summer sale. I was previously using an upturned desk light bounced off the wall, so this is a great upgrade. However, Logitech’s software isn’t great. I suffer it for my mouse (it’s mostly set and forget), but it’s rather annoying to use for a light that’s constantly going on and off. I want to control the light via a macOS shortcut and run it from Alfred. I thought that would be easy. It wasn’t.¹

Update!

In the interim month since I originally wrote this post, a new entry into the app space has appeared. Tim Rogers’ litra-rs project has popped up. It does everything I need and is quite a bit simplier to implement in a shortcut. The same process applies as below but with the new package and commands. There’s even a separate auto-toggle app that will turn on the light when your webcame is active.

Control your USB-connected Logitech Litra lights from the command line

Usage: litra <COMMAND>

Commands:
  on                Turn your Logitech Litra device on
  off               Turn your Logitech Litra device off
  toggle            Toggles your Logitech Litra device on or off
  brightness        Sets the brightness of your Logitech Litra device
  brightness-up     Increases the brightness of your Logitech Litra device. 
  brightness-down   Decreases the brightness of your Logitech Litra device. 
  temperature       Sets the temperature of your Logitech Litra device
  temperature-up    Increases the temperature of your Logitech Litra device. 
  temperature-down  Decreases the temperature of your Logitech Litra device. 
  devices           List Logitech Litra devices connected to your computer
  help              Print this message or the help of the given subcommand(s)

Options:
  -h, --help     Print help
  -V, --version  Print version

tl;dr

Use the Litra driver app. It’s now cross-platform (re-written in Go) and you can use it via a small app (or the command line).

Full implementation

Prereqs: install the Litra driver app. Download it from GitHub and unzip. If you want to only use the CLI tools, copy the lcli binary to /usr/local/bin. If you want to use the app, copy the Litra Driver.app to your Applications folder.

If you only want to use the app, you can stop here. If you want to use the command line or Shortcuts, continue.

If you want to build a shortcut for using this light, we need to the command line. The go-litra-driver library has a bunch of helpful commands. This (copied from the GitHub repo) is the list of commands:

This command line interface allows you to control a litra Glow or Beam 
device using the commands described below.

Usage:
  lcli [command]

Available Commands:
  bright      Sets the brightness level (0-100)
  brightdown  Decrements the brightness by the amount specified
  brightup    Increments the brightness by the amount specified
  completion  Generate the autocompletion script for the specified shell
  help        Help about any command
  off         Turn lights off
  on          Turn lights on
  temp        Sets the temperature of the lights (2700-6500)
  tempdown    Decrements the temperature by the amount specified
  tempup      Increments the temperature by the amount specified

Flags:
  -h, --help     help for lcli
  -t, --toggle   Help message for toggle

Use "lcli [command] --help" for more information about a command.

We want the on, off, brightup, brightdown, tempup, and tempdown commands. These get used by Apple Shortcuts to run via a shell script. At the most basic level, we want to turn the light on. That’s relatively simple: lcli on. However, the light remembers previous settings, so if you want the same setting every time you turn on the light (and I do), we need to set a few defaults. I like the light at 35% brightness (lcli bright 35) and 5000K (lcli temp 5000). So, the shortcut looks like the following:

I append the command with > /dev/null 2>&1 to suppress the default output. This is because the Alfred workflow I use to run Shortcuts will always print shell script output to the screen. That’s annoying and I want it to go away.

Things get a bit more complicated if you want to increase/decrease the brightness or temperature. We need to pass an argument to the lcli command. That requires the “Ask for Input” action in Shortcuts, and we pass that input to the shell script as an argument. So, the shortcut pops up a dialog box asking you “Increase brightness by what percentage?” and an input box for a number. brightup and brightdown increase or decrease the brightness by percentage points (in whole numbers). tempup and tempdown increase or decrease the temperature by K.

All the up/down shortcuts are the same, just with different commands.

I have a few other shortcuts that invoke a specific brightness or temperature (Dim is a low, warm light). These are just iterations on the above method.

Et voila! We can now control a Logitech Litra Glow (or Beam, the process is identical) via the macOS Shortcuts app.

Footnotes

Huge shoutout to Paul Hubbard. This post started the whole process for me (via Luke Stein); however, it’s a bit fiddly and doesn’t include all the functionality I wanted. If you just want to turn the light on and off, follow Paul’s instructions.↩︎