Does not compile multi-file project in PlatformIO, Arduino framework

[maxgerhardt]

@wasp

TwoWire &I2CBME = Wire;
Adafruit_BME280 bme;

What are you doing in that header file.

2nd Project with same Dev Board and same display wont compile

The header is included a maximum of once per translation unit (.c/.cpp) file. If the header creates a global variable instead of declaring the existance of a global variable, then each translation unit will create another instance of that global variable and you get a nice little explosion at the final linking stage (see your log). Thus, multiple definitions. #ifndef MAIN_H #define MAIN_H // Definition. makes KABOOM if more than one .c/.cpp file includes this header int my_global_var; #endif v…