On Wed, 2021-12-22 at 14:14 +0100, didier gaumet wrote: > > Le mercredi 22 décembre 2021 à 11:54 +0000, Tixy a écrit : > > > > I can't see how that is relevant, this is your printer's USB > > connection > > not some old style asynchronous serial interface like RS232. > > > > Hello Tixy, > > Gene is talking about a UDB 3D printer, not about a USB printer, and it > is common for these devices (as for numerous lab devices) to rely on > some form of old-style serial communication, even through USB. > > the USB ACM Wikipedia page: > https://en.wikipedia.org/wiki/USB_communications_device_class
Yes, but there's a difference between a serial style communications protocol, and a physical serial bus which needs a baud rate etc. to be set up. I guess it's possible to use a USB to serial chip in the printer which then talks to a serial interface on the computer driving the printer. But that is very clunky and surely not a bodge that's been needed in the past decade given the ubiquitous USB support in SoCs. OK, let's do a little research... Googling "biqu bx 3d printer" gets me a review [1] which says the printer uses "a powerful 400 Mhz STM32H743IIT6 Cortex M7 CPU". Googling "STM32H743IIT6" gets me supplier [2] linking to a datasheet [3] which says amongst the many peripherals on that SoC are 2 USB OTG interfaces, and it even includes the PHY for that. Also, googling the USB vendor and product IDs Gene gave, shows several places claiming this is a 'Virtual COM Port' from STMicro (the manufacturer of the above SoC). All told, it seems highly probable that the USB connector on the printer is connected directly to this SoC and not via some intermediate serial interface which needs a baud rate configuring. [1] https://3dprintbeginner.com/biqu-bx-review/ [2] https://www.mouser.co.uk/ProductDetail/STMicroelectronics/STM32H743IIT6?qs=FNcb6ahWXRzE163cq8Rfjg%3D%3D [3] https://www.mouser.co.uk/datasheet/2/389/dm00387108-1799185.pdf -- Tixy
