Just bought 50A Deluxe Kit but I have 2 questions:
1. Whether I need to buy an USB (OpenEVSE Programmer)?
2. What is the function of USB to serial comm?
The programmer is not required as the firmware is pre-loaded, however we do release cool features and improvements pretty frequently so at some point you may want to load new firmware.
The USB serial comm can be used to send control commands to adjust current, settings, stop/start, etc.
Here's how to adjust the current settings: