Yo Achim!
> I just added a u-blox 6 GPS mouse, and split the SkyTraq PPS to go
> into GPIO 4 and GPIO 18. So three PPS on one RasPi. I'll post
> results later today, first I finish to compiling the new kernel with
> the new multiple PPS patch.
I'm comparing SkyTraq PPS to the u-blox 6 USB PPS.
Yo Achim!
On Tue, 30 Jan 2018 22:45:39 +0100
Achim Gratz via devel wrote:
> Gary E. Miller via devel writes:
> > I have some u-blox 6 that are USB mice. I get under 2 uS jitter on
> > a RasPi, but I have not compared them directly to a GPIO PPS. I
> > should add that to my long list. It takes
Gary E. Miller via devel writes:
> I have some u-blox 6 that are USB mice. I get under 2 uS jitter on a
> RasPi, but I have not compared them directly to a GPIO PPS. I should
> add that to my long list. It takes a few days for the clocks to settle
> in.
Both my NaviSys stick (uBlox6) and puck (
Hal Murray via devel writes:
>> PPS line discipline via USB virtual serial works and produces the expected
>> ~1ms offsets due to the USB poll interval. It should be possible to remove
>> that shift by doing a loopback measurement via RTS/CTS eventually. Jitter
>> is roughly on par with the local
Yo Achim!
On Tue, 30 Jan 2018 21:58:57 +0100
Achim Gratz via devel wrote:
> It seems to converge pretty nicely and with
> jitter around 40µs now (around the same as LAN jitter).
I have some u-blox 6 that are USB mice. I get under 2 uS jitter on a
RasPi, but I have not compared them directly to
Achim Gratz via devel writes:
> PPS line discipline via USB virtual serial works and produces the
> expected ~1ms offsets due to the USB poll interval.
Actually, that 1ms offset was due to the fact that the serial interface
uses negative logic and I really need to align to the clear edge, not
asse
> PPS line discipline via USB virtual serial works and produces the expected
> ~1ms offsets due to the USB poll interval. It should be possible to remove
> that shift by doing a loopback measurement via RTS/CTS eventually. Jitter
> is roughly on par with the local stratum-1 over network.
The U
Achim Gratz via devel writes:
> I've ordered a bunch of RS232 converters and USB UART today along wth
> another rasPi 3B and Tinkerboard, so I should be able to tell how much
> better things get exactly when you use line disciplining on a virtual or
> real serial port on these and also a PC soon.
Trevor N. via devel writes:
> If you're also going to test on a PC, you might be interested in
> a Linux parallel port PPS driver I modified a while back to add
> low-latency loopback echo and a mode that uses polling instead of
> interrupts for pulse capture. Also, on load the driver measures IO
>
