On 20-08-18 04:33, Udo van den Heuvel via devel wrote:
On 19-08-18 18:22, Achim Gratz via devel wrote:
The trouble with GPIO is that it's either only
available on a few boards that aren't very widespread and PCI(-e) cards
(aside from the LTP cards)
So LPT cards would be acceptable, usable?
In such case:
I'd see a setup with a USB connection for the data part of the setup.
PPS goes to LPT (ack pin).
LPT strobe could be used to send pulse to the ublox(*1).
At the ntpd level I could use the pps driver for pps reception, this
should work with LPT port as well.
With some NMEA messages configured (*2) we could use these for the NMEA
driver for just the date/time part.
Once the ublox driver is in ntpsec things change a bit:
ublox driver (see
https://lists.ntpsec.org/pipermail/devel/2018-August/006444.html) needs
to be changed to use LPT for PPS input and pulse output. But when will
we see the ublox driver as it is in ntpsec?
Do I need to enter a feature request?
How to get the timemark kernel patch into Linux?
Do we really need it? (can we work around it?)
Udo
*1: see https://lore.kernel.org/patchwork/patch/237682/ where the LPT
pps generator is declared BROKEN; this driver (see
https://lwn.net/Articles/373193/) could still be the basis to simply
send a pulse when called as clear edge is not so important, we can
loosen the no-interrupt time considerably?
*2: NMEA implementation in ublox is not as complete as the ublox
protocol is, so how to best configure the ublox? What tooling?
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