Most embedded System-on-chips come with an UART or TTL integrated into the System-on-chip to allow debugging, firmware replacement or serial connection.
The GnuBee Personal Cloud routes the UART connection to a 3.5mm (1/8") Audio Jack for convenient use.
The GnuBee USB to UART uses a Winchiphead CH340G USB to serial chip from Nanjing QinHeng Electronics Co.,Ltd. to convert the UART signal to USB.
The Linux kernel identifies this chipset as the "QinHeng Electronics HL-340 USB-Serial adapter"
Users of other Operating Systems can find drivers in the drivers directory.
Common methods to change firmware in case of any problems.
I use [GNU Screen]https://www.gnu.org/software/screen/ AND [tftpd-hpa]https://packages.debian.org/buster/tftpd-hpa
screen /dev/ttyUSB0 57600
Windows users can download an install PuTTY AND TFTP32)
Baud Rate: 57600 / Data Bits: 8 / Parity Control: NO / Stop Bits: 1 / Handshake: NO