Arduino Mini USB serial adapter. This board converts a standard USB connection to the 5V TX and RX an Arduino requires for communication. You can connect straight to the Arduino Mini or other microcontrollers, allowing them to talk to the computer.
74.316066 usb 6-1: new full speed USB device using uhcihcd and address 4 74.509490 usb 6-1: configuration #1 chosen from 1 choice 74.513157 ftdisio 6-1:1.0: FTDI USB Serial Device converter detected 74.515847 usb 6-1: Detected FT232RL 74.515909 usb 6-1: FTDI USB Serial Device converter now attached to ttyUSB0 Usage of the jumper When searching on the internet, it is unclear what is the role of the jumper. Initially, I thought this was to swicth between 5v and 3.3v, but this is actually not the case. Instead, the jumper is used to enable/disable the 5V power coming from the USB. Links.