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Archive for December 2014

Non-Arduino Adafruit OLED Display Library

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Adafruit sells a really nice 16×2 OLED display and they even have an Arduino library for it.  However I only have a Atmega32 and Arduino does not run on the Atmega32.  Rather than spending $20 or so for an Arduino, I decided to port their library to AVR.  It wasn’t too difficult since Arduino is just AVR C++ behind the scenes.

Re-writing the Adafruit library was straightforward.  I hardcoded PORTA as the I/O port but some additional code could make that generic.  I had to re-write the digitalRead and digitalWrite functions to read and write out of PORTA instead of the Arduino pins.  The delayMicroseconds command is replaced by the AVR _delay_ms() macro.

The trickiest part was figuring out how to implement the print function.  After some digging around I found it in the Arduino code at \hardware\arduino\cores\arduino\Print.cpp.  The print function calls a write function that iterates through the character string which then calls our native OLED write on each character.  This seems seems a little roundabout but I guess that is how they chose to implement it.

Adafruit 16x2 OLDED display

Links:

My No-Arduino code:
https://bitbucket.org/xyzio/avr-code/src/master/characterOLED/

Adafruit Arduino library:
https://github.com/ladyada/Adafruit_CharacterOLED

Youtube demo:

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Written by M Kapoor

December 26, 2014 at 3:02 pm