The three days I am working on SPI. It is a little hard to route, but I added SPI interface to the pins finally.

The upper shows the SPI pins export map. The advantage of this version is all GPIOs(it is real, all 28 GPIOs have exported), and SPI interface is exported too.

The disadvantage is GPIO14, GPIO15 are too near each other, if you solder a connector to GPIO15, it might cover some of GPIO14.

I have tried many ways to make the two GPIOs to be together peacefully, but looks like there is no prefect solution.

If you have any good idea about this, please leave a comment. 🙂