Firmata: how to set a particular pin to high on boot?
It would seem you are right. If I understood the source correctly,
Firmata initializes all digital pins as OUTPUT LOW. Hard to believe, as
this seems like a silly thing to do... My understanding is that:


setup() calls systemResetCallback() in order to set the initial
pin configuration (line 779) 
systemResetCallback() loops over all pins and calls
setPinModeCallback(i, OUTPUT) for every pin i that is not an
analog pin (line 732)
setPinModeCallback() calls pinMode() to set the pin to OUTPUT
(line 325).


If my understanding is correct, then the simplest solution would seem to
patch systemResetCallback() and replace OUTPUT by INPUT on
line&nbsp;732.