[ntp:questions] More than one PPS source on Raspberry Pi?

Paul J R me at pjr.cc
Mon Dec 4 17:02:23 UTC 2017

The answer is no and yes (and also maybe)..

no because the current pps-gpio driver only loads a single pin (though 
it could be extended to load more than one, but i dont think anyones 
done that).

yes because the other way it could be achieved is to create a second 
module called pps-gpio2 and then init that with a different pin config, 
and that wouldn't be overly hard and possibly easier than trying to 
extend the existing driver (depending on knowledge of kernel drivers).

Lastly, maybe because im unaware of what hardware limits the rpi might 
have which might get in the way of doing something like that (from what 
i've read, every pin is capable of being configured for interrupts, so 
it sounds like it should be possible)

On 05/12/17 03:35, Frank Wayne wrote:
> Has anyone tried to use more than one PPS source at the same time on a Raspberry Pi? The device tree overlay pps-gpio does not seem to support more than one instance. That is, if my config.txt specifies two instances of pps-gpio for different GPIO pins, only /dev/pps0 is created.
> The documentation for pps_gpio is limited or missing, and the Raspberry Pi forum and the LinuxPPS list have not helped.
> If pps-gpio cannot do it, is there another way to get PPS devices for Raspbian or another OS that will run on a Pi?
> Frank Wayne
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