This article will shortly recall the basics of SPI, it will also explain how to design a portable software driver in C language, and it will show a few waveforms of the SPI signals generated by the software driver.

I2C or SPI communication this is the question!
Serial Peripheral Interface Bus (SPI) was established by Motorola and Inter Integrated Circuit (I2C) was invented by Philips. So the main protocols to consider are: SPI protocol and I2C protocol.