JSON is a human-readable file format for data storage, and it's what pd2dsy uses to help translate your Pd patch into something that will run on a Daisy-based board. If you haven't worked with something like it before, it might look a little strange, but don't worry! We'll cover enough here to get you on your way to custom hardware in no time.

For most hardware descriptions, there are only three JSON concepts you need to know: numbers, strings, and objects.

Numbers are just numbers! They can be integers (1, 2, 3) or any real number (3.141), and don't need any special formatting or indication.

Text data is stored as "strings", which are strings of characters enclosed in double quote marks ("like this :O").

An object is a set of name, value pairs, enclosed in curly brackets. Each name is a unique string, and each value can be a number, a string, or another object. The name and value are separated by a colon. For a simple object, you might just have one name with a simple value:

{ "pin": 15 }

When things get a little more complicated, such as objects with mutliple pairs, the pairs are usually broken up into their own lines for readability:

{
    "component": "Encoder",
    "pin": {
        "a": 12,
        "b": 11,
        "click": 0
    }
}

An object with multiple pairs must have commas between each.

To make editing JSON by hand easy, it's usually best to use a program that provides syntax highlighting (like the colors you see on this page). VS Code is a great cross-platform tool for this. Of course, you can just use a normal text editor, but errors may be more difficult to spot, and some may even mangle the text in undesireable ways.

To describe a board, your JSON will need an object with a few critical pairs:

• name
  • This describes your project name and determines the names of automatically generated files
• som
  • This is the SOM (system-on-module) that your project uses. This will usually be the Daisy Seed, but can also be the Patch SM.
  • The exact strings are:
    • "seed"
    • "patch_sm"
• audio
  • This is an object describing your audio layout. For most projects, this will simply have a single pair describing the number of audio channels:

{ "channels": 2 }

• components
  • This is the meat of your description. Here, you'll describe all the input and output components of your design such as knobs, CVs, LEDs, and so on. The name determines the receive or send name in your Pd patch, and must have an object with a "component" name. For example, a gate input could be described as:

"components": {
    "myGateIn": {
        "component": "GateIn",
        "pin": 20
    }
}

• More complicated objects may have more required fields.

So, a very simple but viable board description might look like:

{
    "name": "MyProject",
    "som": "seed",
    "audio": { "channels": 2 },
    "components": {
        "myGateIn": {
            "component": "GateIn",
            "pin": 20
        }
    }
}

If some details are still unclear, the JSON descriptions for the built-in boards might help.