The simulator comes with peripherals (such as LCD displays, LEDs, etc.). To load these for your project add a peripherals section to your simconfig file. You can pass in the pin names via "PinNames.p5", these will be automatically resolved on startup. Note that you can change the peripheral config at runtime by clicking Add component. This is then cached by the browser. To clean the cache run sessionStorage.removeItem('model-dirty') from your browsers console.
For an example of how a peripheral looks like, see mbed-simulator-hal/peripherals/Sht31.
A peripheral consists of a C++ implementation, a JS HAL file and a JS UI file. Peripherals in the mbed-simulator-hal/peripherals folder are automatically picked up at compile time. In your own project you can add a section to simconfig:
"components": {
"jshal": [
"./ui/js-hal.js"
],
"jsui": [
"./ui/js-ui.js"
]
}The C++ component is automatically picked up. The JS files are loaded when you run the project. Note that all jshal and jsui files will be copied to the BUILD directory, so to change things on the fly, edit those files (or create a symlink).
You can communicate between C++ and JS through ES_ASM macros (C++ -> JS), or via ccall (JS -> C++). See the components that ship with the simulator for examples.