On 09/04/2019 06:44 PM, Cédric Hannotier via USRP-users wrote:
On 2019-09-04 19:07, Marcus D. Leech via USRP-users wrote:
Le 04.09.2019 19:07, Marcus D. Leech via USRP-users a écrit :
The "set_time_now()" operation is unsynchronized--it simply transfers
the host time to the device(s) without any hardware synchronization
pulse. Since it necessarily has to send multiple commands across
the host-to-device interface, and the device sets its clock
immediately
to whatever value is provided, and the clock continues to run, then
two or more devices will not tightly agree on the time when using
this method.
The issue is that there is only one device. With "set_time_now()", two
daughterboards on the same device (same motherboard) behave as
unsynchronized.
That's because, for weird internal reasons, there are actually TWO
time-of-day clocks on X310 and B210--one per "side". I don't remember
whether there are two commands sent from the host side, or a single
command, that is acted-upon serially within the FPGA. With a
1PPS synchronization, the 1PPS causes a parallel load of the desired
time value into the time-of-day clocks on the motherboard.
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