SPI.setBitOrder(MSBFIRST); // Not strictly needed but just to be sure. SPI.setDataMode(SPI_MODE0); // Not strictly needed but just to be sure. // Set SPI clock divider to 16, therfore a 1 MhZ signal ...

Similarly to I2C and Serial communications, SPI can be virtualized using software to overcome the physical limitations. Here provides an example of using software SPI with Arduino. What is SPI Serial ...

So here’s the thing: Arduino’s built-in memory is tiny. If you’re just blinking LEDs, no problem. But the moment you try to log data, say battery usage, temperature over time, or GPS coordinates, ...