I need to know details about the SPI implementation on Photon, e.g. how to set SPI speed, does it support SPI transactions.
On Arduino IDE I know where to look for header files and top level code files, e.g. for SPI, for every platform installed.
Where do I find this information for Particle Photon?
You don’t need to include anything to get access to the SPI object.
All is there with Particle.h which is included automatically when working on an .ino file.
But in order to know what’s possible and how, I’d rather look at the reference docs than ploughing through header files 
See top of this forum page
leads to
leads to
https://docs.particle.io/reference/firmware/photon/
where you’ll find
https://docs.particle.io/reference/device-os/firmware/photon/#spi
However, if you really need to look at the actual implementation of things you can look at the open source repo
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Thank you, this really helped me to start. Now I got the first update on my e-paper controlled by the Photon.
I had mixed up SPI and SPI1, because I didn’t look good enough at the Particle Datasheet. I took the wrong pins.
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