Custom board definition (MYBOARD.py) and pin aliases

Assuming that the MCU is already supported by Espruino (STM32, ESP8266, nRF5x etc.), how would one define pin aliases (e.g. ADC=D1) without sacrificing a JS variable (e.g. RAM-constrained board) ?

It does not seem to be sufficient to add

devices = {
  'ADC' : { 'pin' : 'D1' },
};

to MYBOARD.py to have ADC automatically available as a global variable in JS as an alias to D1

It's a bit of a hack at the moment - LEDs and Buttons are treated differently.

The best method is to make your own jswrap_xx.c file, and to put something like this in it:

/*JSON{
  "type" : "variable",
  "name" : "ADC",
  "generate_full" : "JSH_PORTD_OFFSET+1",
  "return" : ["pin","My ADC"]
}*/

Right! I had not thought of that... :)

I have 2 goals (not mutually exclusive):

1. avoid repeating ADC=D1 in every program (convenience)
   
2. avoid "burning" JS variables on simple aliases (resource optimisation)
   
   

I guess this solution addresses 1. but would there be a way to address 2. as well ?

It doesn't burn JS variables either - it's one of the big things about Espruino - that all built-in variables/functions exist without taking up any RAM :)