[time-nuts] NIST time services

Mike George mgeorge at tuffmail.us
Sat Mar 22 19:00:48 EDT 2014

The PRU on the BeagleBone each include an enhanced capture module that 
can be used as you describe.
It has a 32 bit timer that is latched into one of the capture 
registers.  The timers are independent of
the timer used by the Linux system so I'm not sure how you would tie 
them into use with NTP.  But they
do look like they would be useful for monitoring a GPSDO as Chris 
described.  There are 4 capture
registers in each eCAP so they would also be useful for 
monitoring/timestamping other signals.

On 3/22/2014 17:44, Hal Murray wrote:
> albertson.chris at gmail.com said:
>> Would you know which other systems include the PRUs?  Is it only in the TI
>> products?   It seems like an ideal solution to the problem of
>> non-deterministic latency.
> There is a much simpler solution - avoid the latency by using a counter/timer
> to capture the counter on an external event.  (That may assume you are using
> the same counter for timekeeping.)  Many ARM chips come with a blizzard of
> peripherals. Good counter/timers are common.

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