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Mallgan.O
Can you elaborate too please? This USB reliability issues is one of the main reasons I am doing this.
To make things short: there is no way to avoid a ground connection when using USB, it's simply a shortcoming of the USB specification. This has been discussed in this forum a number of times already.
Way to get a reliable connection anyways:
- Using Ethernet instead of USB. Requires quite some complexity on the controller electronics, of course. Duet electronics does this.
- Putting an optocoupler between USB-serial converter and controller CPU. Can be done right on the controller board, but you still need the serial link in between, no on-chip USB. Also take care to keep the PC connected USB strictly separate from the printer power supply connected remaining controller.
- There are USB transceivers, sort of an optocoupler for USB. Simpler than Ethernet, more complex than when using a serial line.
- Print from SD cards. That's why SD cards are so popular.
The really silly thing about USB is, the protocol doesn't allow to recover stalled connections. Can be done manually, though, that's why some controllers have a jumper to disable auto-reset (for avoiding a reset when reconnecting).