[RK3568] Unable to Access UART Port

    Hey y'all, am new to this forum so I apologies in advance for the inquiry—in case it does not suit well.

    I am getting desperate as I have been tweaking this motherboard for weeks, I have made some progress on understanding the HEX commands that toggle activity within the machine itself (rotating motors, enabling Serial Ports, etc.)

    The motherboard itself seems to have been by Reyeah, and their customer service is terrible so I were unable to obtain as much information as to how to activate payment methods within the VMC.

    I have noted that the VMC is accessed through the /dev/ttyS0/ port, and through my gathered documentation, I sense that the payment methods are handled through UART. I am attempting to install an ITL Bil Acceptor (Innovative Technologies) which runs on the SSP Protocol. The bill acceptor does power on when I connect it to the appropriate port, however it does not establish any communication—I send multiple HEX commands through /dev/ttyS0 as it is the only accessible port.

    No new tty or related devices are created whenever a device is plugged in/out. The Bill Acceptor does run properly on a PC including the HEX commands (setting it up as SSP).

    The machine came "configured" with a Nayax Credit Card acceptor, and that one (according to the original app's code) seemed to be connected through /dev/ttyUSB5 (though said port does not exist on my machine). Furthermore, I am unable to do any testing even with the Nayax acceptor—it does not receive HEX commands either.

    Could it be that the VMC is locked in some way for access, or am I doing something wrong with attempting to connect to these devices? As I mentioned, the motherboard/master is the /dev/ttyS0/ connection—I believe there should be a way to connect to the slave devices.

    I also tried accessing ADB Shell's configuration and could not find anything related to the devices, not even the fiq_debugger.

    Attaching a sample picture (directly from Reyeah when they "attempted" to assist me) of the motherboard which supposedly contains the RK3568 chip, as well as the Bill Acceptor's port—which I assume is a UART.

    Hope someone can guide me on the proper way as I am getting desperate now! Thanks in advance