Hi everyone!
I recently received my Tevo Tornado. Assembly was easy and the first prints came out nicely.
But when I attached an Raspberry Pi 3 and connected Octoprint to the Tornado, the USB connection got lost repeatedly after about 1 minute.
I tested 4 different USB cables, compiled a new firmware with a lower baudrate (115200 instead of 250000), but nothing helped.
dmesg showed one error message saying "usb_serial_generic_read_bulk_callback: -urbstopped -32" per disconnect.
Then I tested the connection with Cura3 on a Windows machine. Here the connection worked without hangups. I guess the windows driver is more tolerant than the linux one....
This was when I remembered the fake FTDI chips that were in the news a few month ago. I checked the serial number, and indeed, it is one of the counterfeit chips.
Today I completely disassembled the Tevo control box, took out the control board and desoldered the bad FT232RL. The genuine replacement now works flawlessly
While I'm at it, I will also fix the horrible wiring and build a custom frame under the printer from aluminium extrusion.
Hope this helps if someone has the same problems with the serial connection under linux