[Discuss-gnuradio] Synchronize host and USRP N210

[Bastien Auneau]

Hi Everyone

Here are several questions related to USRP N210
1. Considering USRP N210 with GPSDO. Is it possible to use the "PPS in"
of the USRP as PPS out ? Can I just put in contact all 3 pins with the
jumper j510 ?
Will the PPS still be good enough once split ?
I'm interested in this to keep the host PC in sync, linking PPS to RS232
PC port, and monitoring rising edge.

2. About size_t uhd::device::send(...)
It says "This is a blocking call and will not return until the number of
samples returned have been read out of each buffer"
Does this mean that function call returns when all data to be
transmitted has been copied to USRP memory ?
What is the size of USRP N210 memory for sending data with daughter
board WBX-FE-Simple ?

Considering the timeout, if a timed data to transmit is bigger than
internal USRP memory, and tx_timestamp occurs after timeout, then the
data will never be sent ? Or never sent entirely ? Is this the case
mentioned in doc as "Under a timeout condition, the number of samples
returned may be less than the number of samples specified."

3. When using time_spec_t  uhd::usrp::multi_usrp::get_time_now(...)
what is the typical delay to expect before the function returns ? (still
with USRP N210) Can I rely on this call to get precision around 10 - 20
msec ?

Bastien