Erlang seems like a strange choice for deeply embedded hard realtime systems that aren't supposed to ever crash. It's a different set of tradeoffs than Erlang makes.
Erlang was designed for running telephone exchanges - about as deeply embedded hard realtime a system as you can get, that needs to be fault tolerant otherwise 911 goes down.
Erlang is typically used for soft realtime systems on fairly powerful non-embedded hardware. There have been attempts to use it in hard realtime systems, but no successful ones that I'm aware of.