[LinuxPPS] assert/clear

[Remco dB]

On Thursday 29 July 2010 15:25:10 Miroslav Lichvar wrote:
> On Wed, Jul 28, 2010 at 02:16:42PM +0200, Remco dB wrote:
> > E.g. here cat /sys/class/pps/pps0/{clear,assert} (clear being the
> > 'active edge' due to the inverter in my interface) yields:
> >
> > 1280318924.000001384#3929837
> > 1276389352.168599915#265
> >
> > This system is running good and is within +/- 2us 'on time' with an
> > offset within the 5 - 35 ns range averagely.
> 
> 5-35ns offset is very impressive, is that the offset reported in
> loopstats?
> 

No, RRD-tool makes an average (with the AVERAGE option). 
I reckon that this is representative enough. Look at: 
http  remco.org/ntp/helium-ntp-offset.png

RRD-tool gets its data with the command ntpdc -c kern

Bear in mind that the PLL-clock crystal (14.31818 MHz) of helium is thermally 
stabilized.

Remco