For testing I've used the Arduino nano to emulate two devices, one I2C photoresistor sensor and one SPI PWM LED. These devices, for example, could be two different attiny85; but as the atmega368p is ...
This is an example test library for the Epson M-Gxxx/M-A352 Sensing Units (SU) using the SPI interface. It was specifically developed for use with the Arduino Teensy 3.6 development board (Teensyduino ...