On 09/30/2020 01:32 PM, Clark (US), Kenneth C via USRP-users wrote: > Hello, > > The B210 has separate connectors for a 1-PPS and 10-MHz reference. > > But the B205 has only the one SMA connector, which is indicated to be dual > purpose (1-PPS or 10-MHz). > > Is it possible connect both, using a GPIO pin for the 1-PPS? > > If so, which pin? How to enable? > > Thanks, > > Ken Clark The B205 external clock apparatus is quite different than on other USRPs. Rather than having an analog clock PLL chip, there's a DPLL implemented in the FPGA. That DPLL automatically "figures out" whether you have 1PPS or 10MHz coming into the external clock input--of which there is only one. Once it figures that out, it automatically steers the internal VCTCXO based on the estimates of the internal-to-FPGA DPLL. My recollection is that you set PPS to "internal", and REFCLOCK to "external", and it will act appropriately. You *could* re-jig the FPGA code to have both a 10Mhz reference, and a 1PPS coming in on a GPIO--but that isn't built in. > > > Ken Clark > Email: kenneth.c.clark2@boeing.com > Mobile: +1 561 398 1050 > DRT, Inc. > > > > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com