Here's the code. Just rename the PDF to Zip and expand it into a folder under your .../Documents/Arduino directory.
The code works well now, though there are a few things I'd like to keep working on. It will drive one of the I2C 1" OLED displays. I typically comment this out at line 101 in the main program (EDIT since I don't use the display in the amp)...
// If not using display just don't create it
activeOLED = new OLED (128, 64,SSD1306); // I2C Display
//activeOLED = new OLED (128, 64,SH1106, OLED_MOSI, OLED_CLK, OLED_DC, OLED_RESET, OLED_CS); // 1.3" SPI Display
I'm happy to keep working on it. I can post the Gerber files as well at some point.
VolumeController.pdf -> rename to VolumeController.zip
EDIT: I just wanted to add a note that this will work on an Arduino UNO or Pro Mini. Pretty much anything with an Atmel 328P. Could probably support other chips as well.
EDIT 2: This code will run the older and larger I2C boards (requires a slight code change) as well as version .4 and .5 of the current SPI boards.