This became possible very recently to sample accuracy thanks to a firmware modification. Check this post on the limesdr mini:
On the limesdrUSB, the same firmware mod can be implemented. It’s few lines in the vhdl code, but you need to sacrifice one of the fpga gpio’s for that, whereas limesdr mini uses egpios. As we now have limesdrUSBs back on the track, that very nice sync feature might be implemented in firmware? (@VytautasB )
