Hardware abstraction layer (HAL) for communicating over TWI/I2C with the display. Basic settings like the speed of the bus can be defined in twi.h.
Hardware-defined TWI makes communication inflexible with regard to ports, as these cannot be switched.
TWI-Bus speed definition
The TWI transmission speed can be set up within the F_TWI macro (100 kHz is set by default).
#define F_TWI 100000UL
Prescaler for TWI clock generation
The TWI bitrate register can only take 8 Bits so it is necessary to setup the correct prescaler. The faster the bus goes the lower should be the prescaler.
Calculation of the bitrate register (allowed values: 1-255):
#define TWI_PRESCALER 0
Valid prescaler values are
0,1,2, and3, representing division factors of1,4,16, and64respectively.
For a more detailed view of the possible parameters that can be set in twi.h, take a look at the OLED Doxygen documentation (OLDD).