epaper_spi does not describe rotation direction

[avg-I]

Feedback

To quote:

rotation (Optional, int): Set the rotation of the display. Everything you draw in lambda: will be rotated by this option. One of 0° (default), 90°, 180°, 270°.

But this does not describe in which direction the rotation is done (if it's not 180°).
I do not think that there is a universally accepted default rotation direction.

URL

https://esphome.io/components/display/epaper_spi/

Additional information

No response

[kepstin]

It's pretty universally accepted that if unspecified, the rotation is clockwise in the positive direction. I don't think any extra clarification is needed here. That said, something that might be confusing is whether it's referring to how the content should be rotated relative to the screen, or whether you set the physical rotation of the screen and the content is rotated backwards to correct for it.

Also note that although the rotation parameter is documented in the epaper_spi component, it's actually a common parameter of all graphical display components, where the description says:

rotation (Optional, integer): The rotation of the display in degrees, one of 0, 90, 180 or 270. Defaults to 0.

Something I noticed is that I don't think the default rotation for every display is actually 0°. For displays integrated into devices (rather than on breakout boards or HATs) the default rotation might be set to a value which is appropriate for how the display is mounted in the device.

[avg-I]

Thank you, @kepstin. That's a very good correction / clarification of the issue.

[clydebarrow]

I don't think the default rotation for every display is actually 0°.

All the modern display drivers use 0 as the default rotation. The deprecated ili9xxx driver did have some built in hardware rotation for some devices, but the principle applied now for epaper_spi and all the mipi series drivers is that you get the native orientation by default, thus minimising surprises.

[clydebarrow]

That said, something that might be confusing is whether it's referring to how the content should be rotated relative to the screen, or whether you set the physical rotation of the screen and the content is rotated backwards to correct for it.

This is a good point. The convention used in ESPHome is that a rotation of 90 will cause the displayed image to rotate 90 degrees clockwise.