Hi! I reinstalled everything from scratch with a new Armbian, AVRdude and octoprint. I still have a serial connection error, it seems that ttys5 is not connected / recognized. I've search many forums and docs but could not find an answer... How can I check if the device is really connected? I have an access to the Atmega with AVRDude, but not serial... For now I have the following unexpected results: `>stty -F /dev/ttyS5 -g stty: /dev/ttyS5: Input/output error`, `>setserial -ga /dev/ttyS5 /dev/ttyS5, Line 5, UART: unknown, Port: 0x0000, IRQ: 0 Baud_base: 0, close_delay: 50, divisor: 0 closing_wait: 3000 Flags: spd_normal` and `>sudo setserial /dev/ttyS5 uart 16550A baud_base 115200 Cannot set serial info: Device or resource busy` @racer, is there a port / GPIO /device configuration that I forgot? Thanks for any help... M.