New 0.5 draft of the SemPiTernal HOWTO

[Frank Nicholas]

> Simple to see:
> 
> root at pi2:~# ppstest /dev/pps0
> trying PPS source "/dev/pps0"
> found PPS source "/dev/pps0"
> ok, found 1 source(s), now start fetching data...
> source 0 - assert 1462492791.999966543, sequence: 147766 - clear  0.000000000, sequence: 0
> source 0 - assert 1462492792.999970614, sequence: 147767 - clear  0.000000000, sequence: 0
> ^C
> 
> No clear edge is every detected, but the assert ticks away.

Gotcha - the “clear” part should be the time of the trailing edge, right?

> Also note my pi2 has ntpd peers, so I know the assert it right on the money:
> 
> root at pi2:~# ntpq -p
>     remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> -SHM(0)          .GPS.            0 l    2   64  377    0.000  -115.17  87.356
> *SHM(1)          .SHM.            0 l    1   64  377    0.000    0.028   0.008
> +catbert.rellim. .SHM.            1 s   20   64  377    0.369    0.407   0.070
> +spidey.rellim.c .GPS1.           1 s   38   64  376    0.355    0.025   0.021
> -kong.rellim.com .SHM1.           1 s   64   64  377    0.313   -9.145   1.668
> -backup.rellim.c 204.17.205.8     2 s   61   64  377    0.423    0.071   3.575
> 
> 8 microSec jitter on PPS, 0.025 milliSec offset from my main GPS PPS server
> (spidey).

And those other peers are not Pi’s?  They have good (leading & trailing) detection?