Often the following code seems to be required (enter on terminal):

stty -F /dev/ttyACM0 speed 1200 cs8 -cstopb -parenb

• Show gcc buildin macros: gcc -dM -E - < /dev/null

• F_CPU must be defined and must expand to the CPU frequency in hertz (e.g. -DF_CPU=16000000L)

• ARDUINO: Version number of the Arduino Environment. 100 for 1.00.
• __AVR__: Atmel AVR
• __18CXX: MPLAB C18 (PIC)
• __PIC32MX: PIC32
• __XC8 MPLAB XC8 Compiler (Microchip)
• __PIC18 MPLAB XC8 Compiler with selected PIC18 device
• __arm__: GCC ARM (Arduino Due)
• __SAM3X8E__: Arduino Due
• __AVR_ARCH__: Values 2 and 25 are ATTiny
• __XTENSA__, __xtensa__: gcc predefined for xtensa architecture (ESP8266)
• ARDUINO_ARCH_ESP8266, ESP8266: Defined by the esp8266 Arduino board file

• U8G_COM_HW_SPI
• U8G_COM_ST7920_HW_SPI
• U8G_COM_SW_SPI
• U8G_COM_ST7920_SW_SPI
• U8G_COM_PARALLEL
• U8G_COM_FAST_PARALLEL
• U8G_COM_SSD_I2C
• U8G_COM_T6963

These communication macros are specific for each environment.