Several years ago, I purchased a Printrbot Metal Plus with a dual extruder option and the LCD attachment/accessory. Printrbot has now gone out of business, and the USB connection isn't working very well for reasons I'm not quite sure of (It has native USB that emulates a UART connection to a computer, but it hasn't connected to Cura since a few months after I bought it, not that I really noticed at the time).
I have been printing via the LCD control accessory for all print jobs since, both due to it being more convenient and due to the USB not working.
Since it would be more convenient (and also because the remaining single point of failure concerns me when dealing with equipment this expensive), I would like to connect an ESP8266 with the ESP3D firmware to my printer. This would allow wireless printing and control of the printer from a web or network interface. I even have several ESP8266 modules lying around waiting to be programmed from an unrelated project.
My problem is that, due to the extra controller board for the second print head and due to the LCD being installed, I am not sure if the hardware UART (there's supposed to be one somewhere, but it wasn't well broken-out since the controller uses USB instead) is being used or is available right now.
I'm also not even sure where on the motherboard it is (assuming it even has one), since, with the folding of the company, most of the documentation seems to have evaporated.
The above URL is the only resource I was able to find with details on that. I read it some time ago, but wasn't really able to map the pins to the board layout or the descriptions on the chip. On my check just now, I wasn't even able to find a UART.
Does anyone know enough about these printers to say where to look for a UART or to tell whether it's used by one of the attachments I have?
I would also be happy with a method to convert a UART to USB and back, assuming that it's my computer that's having issues connecting and not the printer.
I have also tried Octoprint, but that has its own issues, namely that I have to use a Raspberry Pi and that some of the configuration needs to be done on the Pi itself, as well as the corruption possibility and I suspect a different use case. One advantage of using the ESP8266 is that it is mostly safe from corruption and its main software is read-only.
I am not certain what board revision is used in my printer, since it arrived pre-assembled and I'd rather not open up the case (it's really nasty to try to get to, since you have to flip the entire thing over). I would thus appreciate any help you can give in finding any documentation that might say which it is or that directly applies to a board so that I can modify the instructions to suit my case should that part differ.
Similarly, I never was able to figure out what exactly the dual-head daughterboard is despite some effort, and that was back when the site existed still. The documentation was never the best; it was fine up until you need to replace the firmware or figure out what exactly is actually in there, since most of this seemingly wasn't actually written down. IIRC, they even said some time later that they no longer shipped with it, so I have no idea.