I used this driver only on a 128x32 display, so couldn't say either way about this issue. Reading the docs for the SSD1306 it says there are 6 combinations for display configurations (for a size of 128x64 pixels) for this option, so it may be that it's hardware dependent what value to use here.

How do other drivers (Arduino etc) configure this value?

Actually after studying the data sheet w/o getting better clues I tried another driver, which worked, and compared the difference. The setting for SET_COM_PIN_CFG was the only one, and implement that made the driver work. But, as I noted, I tested just that device. Other 64x32 units may behave differently. The 128x32 you used should not be affected by the change.

I did a brief search for SSD1306 tutorials and all seem to rely on Adafruit's driver https://github.com/adafruit/Adafruit_SSD1306/blob/master/Adafruit_SSD1306.cpp. For this setting (grep for SSD1306_SETCOMPINS) 0x02 is the default, and 0x12 is used only for w=128, h=64. Although it doesn't seem to officially support 64x32 displays.

So, maybe it's best here to change the code to 0x02 if (self.height == 32 and self.width != 64) else 0x12. At least that will only have a change for 64x32 displays.

Whatever works. As said, I have not much confidence that the suggested change will work for all devices.

There's only two I know if that use 0x02. Use "sequential" (bit 4 = 0) when there are two sub panels - a panel at the top and one at the bottom. Use "alternating" (bit 4 = 1) when it's a large panel and each com pin maps to even rows, then odd rows, like interlacing.

0xDA, 0x02:

• 96x16
• 128x32

0xDA, 0x12:

• 64x32
• 64x48
• 48x64
• 72x40
• 128x64

Thanks @mcauser for the data. I have a 128x64 SPI based SSD1306 display and I tested it and it does need 0x12.

It looks like a value of 0x02 is used only when the aspect ratio is greater than 2. So that means the formula could be:

0x02 if self.width > 2 * self.height else 0x12

That would lead to smaller and faster bytecode than checking a set of specific w/h values.

Changed accordingly. Thanks for testing. Besides that one, I have only displays with other controllers at hand.

Thanks for updating, merged in 8680a74