The command-line tool has tools to:
  • Build your code to update your PCB
  • Test your design
  • Generate files to order your PCBs from manufacturers
  • Install and manage dependencies
  • Create new projects, components or build-targets
There’s a semi-de-facto standard format for running apps from the terminal, including ato. 
app command [options] arguments
  1. app is the name of the app you’re running.
  2. command is the command; think of it as a “menu option” the app provides.
  3. options are the options for the command, typically zero to many instances of --some-option option-value.
  4. arguments are just like options, but they only take a value. Their position tells the app which argument they are.
Add --help to the app/command/subcommand to get more information at any point.

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Command structure

Some commands might have subcommands. Think of it like a menu where, from left to right you’re choosing deeper and deeper into the menu. If an upper command/app accepts options, those options should go right after the app/command, rather than at the end after subcommands. For example, -v is a special option, called a “flag,” which doesn’t take a value. Its presence or absence is what matters. It increases the amount of information the compiler prints -> increase its verbosity. The -v flag is an app option, so to use it, place it right after the app name. 
ato -v build

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Build process

As a rough overview, here’s what happens when you run ato build:

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Explaining the hello-world project

This tutorial continues from the quickstart guide.If you haven’t already, complete it, and then come back here.
With the explanation of ato code and the build process, it should be a little more clear what’s happening now in the quickstart project. 
import Resistor

module App:
    r1 = new Resistor                # Create a new resistor
    r1.resistance = 100ohm +/- 10%   # Set the resistor value
Here’s a breakdown:
  1. Import a Resistor
  2. Define a new module, named App. This is the entry point of the build (see your ato.yaml).
  3. Create an instance of the Resistor
  4. Set the resistor’s value attribute This constrains what components the compiler can pick for this resistor. For picking, the rated resistance must be wholly within the value attribute. The precise way to say this in more CS terms / what atopile says internally is that the picked resistor’s resistance must be a subset of the quantity interval defined by the value attribute.

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Extending it

Suppose the circuit needs a simple voltage divider - and the standard library doesn’t exist containing one pre-made and tested for you. It’s easy to create your own! 
import Resistor


module VoltageDivider:
    r_top = new Resistor
    r_bottom = new Resistor

    r_top.p2 ~ r_bottom.p1


module App:
    my_vdiv = new VoltageDivider
    my_vdiv.r_top.resistance = 10kohm +/- 10%
    my_vdiv.r_bottom.resistance = 4.7kohm +/- 10%
Now, this is, technically, a voltage divider. And the compiler happily builds it, grabbing the right components etc. But, it’s not a good voltage divider.
  • There’s no clear interface showing how to connect to it
  • The point of a voltage divider is to scale voltage, but it’s unclear what its scaling actually is
  • No documentation describes what’s going on
To fix that: 
import Resistor, ElectricPower, ElectricSignal

module VoltageDivider:
    """
    A voltage divider using two resistors.

    Connect to the `power` and `output` interfaces
    Configure via:
    - `power.voltage`
    - `output.reference.voltage`
    - `max_current`
    """

    # External interfaces
    power = new ElectricPower
    output = new ElectricSignal

    # Components
    r_bottom = new Resistor
    r_top = new Resistor

    # Variables
    v_in: voltage
    v_out: voltage
    max_current: current
    total_resistance: resistance
    ratio: dimensionless
    r_total: resistance

    # Connections
    power.hv ~ r_top.p1; r_top.p2 ~ output.line
    output.line ~ r_bottom.p1; r_bottom.p2 ~ power.lv

    # Link interface voltages
    assert v_out is output.reference.voltage
    assert v_in is power.voltage

    # Equations - rearranged a few ways to simplify for the solver
    assert r_top.resistance is (v_in / max_current) - r_bottom.resistance
    assert r_bottom.resistance is (v_in / max_current) - r_top.resistance
    assert r_top.resistance is (v_in - v_out) / max_current
    assert r_bottom.resistance is v_out / max_current
    assert r_bottom.resistance is r_total * ratio
    assert r_top.resistance is r_total * (1 - ratio)

    # Calculate outputs
    assert r_total is r_top.resistance + r_bottom.resistance
    assert v_out is v_in * r_bottom.resistance / r_total
    assert v_out is v_in * ratio
    assert max_current is v_in / r_total
    assert ratio is r_bottom.resistance / r_total

module App:
    my_vdiv = new VoltageDivider
    assert my_vdiv.power.voltage is 10V +/- 1%
    assert my_vdiv.output.reference.voltage within 3.3V +/- 10%
    assert my_vdiv.max_current within 10uA to 100uA
Much better! This is a better approach. Here’s a breakdown:
  1. When possible, import from the standard library.
  2. Define a new module, named VoltageDivider This means you can trivially have as many VoltageDividers as you want, all configured properly with all the same interfaces.
  3. Document with """
  4. Place external interfaces somewhere obvious Use sensible types, like Power to expose them.
  5. Embed the relationships between parameters with assert Read these statements as “make sure the following is true.”
    1. The output voltage is within the range of the voltage divider ratio equation
    2. The input voltage must be greater than the output voltage
    3. The current through the bottom resistor must be within the allowed range of the maximum quiescent current