In this demo, I use an 128x64 OLED display with an Olinuxino A20 Micro board. I use the in-tree ssd130x DRM driver in the Linux mainline kernel v6.3, allowing me to use X11 to draw to the screen via X11 modesetting driver. The Linux image is created using Yocto Kirkstone.
I use the display in SPI mode. On the Olinuxino board, I connected it to
CLK, MOSI and CS0 of SPI1 (UEXT2 connector).
The DC signal is connected to PH0 (GPIO-3 pin 5), the RES signal to
PH7 (GPIO-3 pin 9).
Apparently some SSD1309 display modules are wired in weird configurations, i.e., they have remapped rows and column and offsets. To configure this, the kernel driver provides multiple custom devicetree bindings (e.g., solomon,segment-no-remap). I found those values by trial-and-error.
To create this demo, I enabled the build of an X server in the Yocto configuration
and installed twm, xclock and mpv (for video playback) and their dependencies.
However, it should also be possible to skip the X server and directly access
/dev/fb0 for simple applications, as the DRM driver also provides this legacy
framebuffer interface. Wayland should work as well.
I use Yocto Kirkstone to set up this demo.
I am using the linux-yocto-dev kernel v6.3. Because meta-sunxi does not provide a defconfig for this kernel version, I supply it in this layer. For a real project, it would probably be better to put this into a separate layer and to only use configuration fragments to enable the ssd130x drivers in this layer.
This yocto layer depends on
URI: https://github.com/linux-sunxi/meta-sunxi
branch: kirkstone
which provides the machine file for Olinuxino-A20 and build recipes.
Adding the meta-ssd1309 layer to your build
Run 'bitbake-layers add-layer meta-ssd1309'
The changes I made to my distro and meta-sunxi are found in /patches.
To build the image, I used
bitbake core-image-x11