ssd1306 wrong resolution on 128x32 OLED about periph HOT 10 CLOSED

@maruel I picked up the device again and found the problem this time.

I looked at how the device was initialized with the adafruit python library (https://github.com/adafruit/Adafruit_Python_SSD1306/blob/master/Adafruit_SSD1306/SSD1306.py#L309). I found a mismatch here https://github.com/google/periph/blob/master/devices/ssd1306/ssd1306.go#L207.

So I replaced...

0xDA, 0x12, // Set COM pins hardware configuration; see page 40

with...

0xDA, 0x02, // Set COM pins hardware configuration; see page 40

And now the display is working properly:

There is no public interface to send commands directly to the display, what do you propose to make something flexible so I can make it work?

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I found out how to do it:

if err = c.Tx(0x3C, []byte{
    0x00, // I²C transaction has stream of command bytes
    0xDA, // set comm pins
    0x02, // 2
}, nil); err != nil {
    return nil, err
}

I am going to close it now :)

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No worries. :) Reopening because this is a bug.

So clearly the COM pins configuration needs to either have more conditions or be made configurable. I think we'll need the later as this really depends on the hardware configuration. :/ Expanding on the doc which isn't that clear;

Bits

• 5 enables top and bottom panel swap
• 4 enables alternative each side instead of using two subpannels

This is coupled with C0/C8:

• C0 means bottom-top
• C8 means top-bottom

It is used to rotate the display.

So we'll need an enum to clarify the above in a way that keeps the rotated functionality working (which I'd prefer if possible).

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FTR, I still want to fix this, I just need to figure out the best way to expose the bit.

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Interesting. Can you try changing this line:
https://github.com/google/periph/blob/master/devices/ssd1306/ssd1306.go#L207
to 0xDA, 0x02, ?

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@maruel nope, same problem.

I don't know if it is relevant/interesting or not but... if I try with -h 32 on the 128x64 display, it displays on the bottom half of the screen (like 1st screenshot, but on the 128x64 device)

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@maruel I feel silly, that was your proposed diagnosis the first time!

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I'm starting to think about v3, this should be fixed in time for this release, which will likely be in a few months.

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@maruel thanks! in the meantime I have a workaround so that's great

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Thank you very much!

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