oled.h - OLED parameter definition

Sep 3, 2025 / Sep 19, 2025

3 minutes to read

Platform selection

The hardware abstraction layer (HAL) of the OLED display currently supports the microcontrollers avr (ATmega16A, …) and avr0 (ATmegaXX08/ATTinyXX06, …), which can be easily switched using the OLED_HAL_PLATFORM macro.

// For AVR platform
#define OLED_HAL_PLATFORM avr

// For AVR0 platform
#define OLED_HAL_PLATFORM avr0

Folder structure setup:

For AVR platform

- ./lib/ + oled/ + oled.h
         |       + oled.c
         + hal/ + avr/ + twi/ + twi.h
                       |      + twi.c
                       + twi_soft/ + twi_soft.h
                                   + twi_soft.c
         ...  

For AVR0 platform

- ./lib/ + oled/ + oled.h
         |       + oled.c
         + hal/ + avr0/ + twi/ + twi.h
                        |      + twi.c
                        + twi_soft/ + twi_soft.h
                                    + twi_soft.c
         ...  

Microchip Studio compiles all libraries in the folders by default. Therefore, either avr or avr0 should be created in the folder structure and the library that is not used should be removed. To select the correct platform and set the clock speed correctly in the libraries, it is best to create a global define under Project-Settings -> AVR/GNU C-Compiler -> Symbols in Microchip studio.

// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
// !! GLOBAL DEFINES FOR AVR0 PLATFORM                  !!
// !! F_CPU=20000000UL                                  !!
// !! OLED_HAL_PLATFORM=avr0                            !!
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Communication mode of the display

Communication between the display and the microcontroller can be achieved either via software-defined TWI or via the microcontroller’s internal hardware in oled.h. Software-defined TWI makes communication more flexible because the ports can be switched.

To use software defined TWI it is necessary to setup the OLED_USE_SOFT_TWI macro (is set by default).

#define OLED_USE_SOFT_TWI

TWI bus details can be set up in twi.h for hardware or in twi_soft.h for software setup.

Address of the display

The address of the display can be defined within OLED_ADDRESS macro.

#define OLED_ADDRESS 0x7F

On some displays the Address is directly in 8-bit mode [8:1]. Note that the OLED_ADDRESS macro takes only 7-bit addresses [6:0]!

Display size settings

There are different displays with different sizes on the market. The library supports different formats that can be set up with the OLED_COLUMN_SIZE and OLED_ROW_SIZE macros.

#define OLED_ROW_SIZE 64UL
#define OLED_COLUMN_SIZE 128UL

It is also possible to adjust the page size (OLED_PAGE_SIZE) but normally on every display it should be 8 (bits).

Save init routine in EEPROM

It is possible to store the init commands in the EEPROM of the microcontroller.

#define OLED_INIT_ROUTINE_IN_EEPROM

This can save some program memory in tiny systems (not enabled by default).

For a more detailed view of the possible parameters that can be set in oled.h, take a look at the OLED Doxygen documentation (OLDD).