The microcontroller is an Arduino Leonardo equipped with an Ethernet shield and a custom prototype shield for the interface with home trainer.
Arduino Leonardo is connected with the computer both with USB port and Ethernet connector.
The USB port is set in HID mode in order to emulate mouse clicks.
The custom prototype shield adapt Arduino TTL digital I/O to RS485 signals for the home trainer interface.
Electric scheme of custom shield:
Wiring of custom shield: