I have this one board. When I start printing pronterface every time cause by this errors:
Print ended at: 13:58:37
and took: 00:01:12
Print Started at: 14:03:08
Error:No Line Number with checksum, Last Line: 66
Error:No Line Number with checksum, Last Line: 66
Error:No Line Number with checksum, Last Line: 66
Error:No Line Number with checksum, Last Line: 66
Error:No Line Number with checksum, Last Line: 66
Error:No Line Number with checksum, Last Line: 66
Error:No Line Number with checksum, Last Line: 66
After I can try again only after psu switching. I exclude PSU noise because I try to use Bench Top DC PSU HY3005C. I also try to use another power supply for AVR and ft232 cuted off and use usb +5v power.
There is one interesting thing which I found. If unplug all motors or only Z motor attached - errors don't appear and pronterface printing normal.