SSD1306 OLED (72x40) I2C display from scratch

[richard]

For any reason, my OLED module won't start up once out of ten or twenty times.


I have no clue why.

Since the module you are using has no provision made for the user to be able to reset it you are totally dependent on how the on board POR circuitry applies the reset signal. The board will have a very definite absolute minimum off period and minimum on time before a successful reset will occur. If you don't adhere to those times then its matters not what you code is trying to do the chip won't necessarily be receptive. If your code still does not work reliably after suitable POR conditions have been met then you code is incorrect. Simply resetting your pic is not enough.

The data sheet gives no clue re command execution time or even if i2c clock stretching is in play, anecdotally there is some support for a small delay after executing an $ae command being beneficial