To use my code you will need one or more I2C OLEDS. These are readily available, and inexpensive. You must buy the 4 Pin I2C versions. My code does not send the reset that some boards with more pins need.

BEWARE: There are several types of 4 pin OLED available. All the ones that I have come across use Address '60d' and this is what my code expects. If you are using the 128*32 small displays, then you will be using separate I2C busses and having the same address for each OLED does not matter.

If you plan on having two 128*64 displays, then my code assumes that one will be set up as Address '60d' (as it came from the shop) and the second display will be Address '61d' (Because you make a small change to the display, move one resistor.). (For some reason, the displays have the address printed as '0x78' and '0x7A', but I will refer to these as '60d' and '61d', as this how the code "sees" them.) The display on the left has been adjusted to '61d' Note that in the photo, the light caught the moved resistor, - it is not a solder blob across the pads, but the edge of the resistor catching the light.

However Jan discovered that there is a type of 4 Pin I2C OLED that is VERY hard to change addresses: it needs some complex and difficult operations to set to 61d so my advice is to AVOID this type of OLED, and always only buy OLEDs that have the simple select resistor address change on the back. - I only now buy from shops that show pictures of the BACK of the display!. To repeat: AVOID these: