How do I set up PlatformIO to use a 'uStepper'?

So I am trying to build a belt-driven linear actuator. I have this board for my stepper motor called a ‘uStepper’.

It has a nice github set up with the library in, and I can download settings to install it as a board within the Arduino IDE, but is it possible to get this working with Atom using PlatformIO? Can I add it in so I can use that?

Otherwise I will just use the Arduino IDE but that’s not as nice, is it?

Thanks in advance for your help. Sorry I’m quite new to this so perhaps I’m asking obvious questions, please help me if so though!

Yes, it’s possible but a little bit more difficult. Nice manual in our docs.
Config for your board based on Arduino Uno:

{
    "uStepper": {
        "build": {
            "core": "arduino",
            "extra_flags": "-DARDUINO_ARCH_AVR -DAVR_USTEPPER",
            "f_cpu": "16000000L",
            "mcu": "atmega328p",
            "variant": "ustepper"
        },
        "frameworks": ["arduino"],
        "name": "uStepper",
        "platform": "atmelavr",
        "upload": {
            "maximum_ram_size": 2048,
            "maximum_size": 32256,
            "protocol": "arduino",
            "require_upload_port" : true,
            "speed": 115200
        },
        "url": "http://www.ustepper.com",
        "vendor": "uStepper"
    }
}

Also you will need to add ustepper folder from this archive to variants in framework package:
/home/user/.platformio/packages/framework-arduinoavr/variants (Unix)
C:\Users\user\.platformio\packages\framework-arduinoavr\variants (Windows)

I’m using OSX, should that .platformio folder already be on my Mac? Or do I need to make it? I can’t seem to find it

@josh-ward Have you already compiled any project?

not yet, I was hoping to set up my board first. do I need to?

Yep, before compiling PlatformIO will download tools and frameworks so simple blink project for Arduino Uno will be enough.

Have I done something wrong now? These error messages come up when I type the boards command in the terminal like the tutorial seems to suggest? Can you help?

Sorry, here is correct config:

{
    "uStepper": {
        "build": {
            "core": "arduino",
            "extra_flags": "-DARDUINO_ARCH_AVR -DAVR_USTEPPER",
            "f_cpu": "16000000L",
            "mcu": "atmega328p",
            "variant": "ustepper"
        },
        "frameworks": ["arduino"],
        "name": "uStepper",
        "platform": "atmelavr",
        "upload": {
            "maximum_ram_size": 2048,
            "maximum_size": 32256,
            "protocol": "arduino",
            "require_upload_port" : true,
            "speed": 115200
        },
        "url": "http://www.ustepper.com",
        "vendor": "uStepper"
    }
}

thank you so much! you have been so so helpful