So was looking into making a few changes and opened up the files in Arduino as I use that for my 3D printers firmware. Seems there is an old link to the for the board manager that no longer works
Searching the forums things go back many years I fear some of what I found is very obsolete.
Let's say I want to lower the temperature threshold it's easy to find in the open_evse.h file but I cannot load the correct board to compile it.
Looking to make some other changes too don't mind setting up a dev environment just need some direction as what is here in the forums seems outdated.
The OpenEVSE source code has a boards file:
But if you want a shortcut, just pick the Arduino Uno.