Trying to develop an own program for Octopus max ez board

[Edgar]

Hello, I am trying to figure out how to write a program for the Octopus max ez board.

What I did so far: I downloaded the Octopus-Max-EZ-master from github and compiled the marlin example. I build the firmare.bin file and I put it on a sd card. Put the card into board and reboted card. Program was transfered and marlin is working  ( its blinking and I can comunicate Gcodes and get answers. So far so good. Board seems to be ok

Next I wanted to put a Blink example program onto the board. So new project, But there is no Octupus Max EZ bord definition in PlatformIO. So I used ST Nucleo 723ZG as board. according Datasheets the MCU is compatible with Stm32h723ZET6.

Wrote a blink program with Pin PA14 and put it on SD, Booloading worked but no blinking.

So next step I rtied to understand the marlin example. But I am lost as marlin is very complex in creating the invironment for the board. 

So I am lost. without a working board definition i can not proceed. 

can s.o. please  help?

regards Edgar