@jschwalbe, ah I see you are now looking here for help… So now I can tell you that my ESP8266 based micro is a Digistump Oak which is somewhat supported by Particle. I say somewhat because it can be very temperamental when trying OTA update it. That said @peekay123 is right, the code will need to be ported to work on the Spark Core (I don’t have one of these).
At a very high level here is what you may run into:
You are going to have to replace the Bylnk ethernet stuff with the appropriate Bylnk Wifi stuff (libraries). That should be straight forward if the Spark Core has the appropriate Bylnk Wifi based library for it.
I ran into this when just trying to compile for the Oak… In Bus_Reactor.cpp one of the functions is trying to manipulate parity (on and off) using some low level functions. My compile quite there with an error. So you may run into the same depending upon how the core functions are implemented for the Spark Core. If so, this will require some changes.
You’ll have to create your own Blynk app (you’ll need a Blynk login) and use the appropriate auth ID in the main sketch.
I assume that the Spark Core is a 3.3V device, so you should match the voltages on the serial lines from the MAX3232 just to be safe. I think simply powering the MAX3232 at 3.3V will work.
Don’t know what else you may run into but I suspect if you can get through the porting required the Spark Core should work. Again, don’t have one so I can’t say for sure.
BTW, what Arduino board/shield combo was this written for? Have you tried to contact the author?