It comes w ntp out of the box if you run fedora. 


On Aug 19, 2012, at 20:21, Bob Camp <[email protected]> wrote:

> Hi
> 
> The pi doesn't have a conventional serial port. It does have a TTL serial on 
> the 28 pin connector. There are also IRQ pins on the same connector. Since 
> they go directly to the CPU chip, hardware latency should be pretty good. It 
> should interface directly to a TTL output gps receiver like a LEA-6T. You 
> probably would need to tune up a driver to get it to work. Since it's Linux, 
> you should be able to get some sort of ntp running on it. AFIK there are no 
> neat counters like on a 45xx board. You also don't have a well tuned ntp 
> since it's LInux.
> 
> Bob
> 
> On Aug 19, 2012, at 1:31 PM, Chris Albertson <[email protected]> 
> wrote:
> 
>> On Sun, Aug 19, 2012 at 10:16 AM, bownes <[email protected]> wrote:
>> 
>>> Why not just use a raspberry pi? Uses a whole 2w at idle. Ntp might bump
>>> that  to 2.01.
>>> 
>>> 
>>> 
>> You certainly could run ntpd on that box.  But I wonder how the PPS is
>> supported in hardware?   What is the standard deviation of interrupt
>> latency on the DCD pin on the serial port.  Perhaps some one who has a "pi"
>> could measure this.   All the data should be in the system log as each PPS
>> is time stamped and written to the log.   If the DCD pin is polled you are
>> not going to get decent results.  Maybe someone could read the PPS drive
>> code.
>> 
>> -- 
>> 
>> Chris Albertson
>> Redondo Beach, California
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