> On 05 Mar 2016, at 07:54, Peter Ankerstål <pe...@pean.org> wrote: >>>> >>> GPIO is supported on the Pi, I'm using it on 11-Current on my home >>> control software to drive relays on my pool hardware (e.g. valves, >>> heater, VFD motor drive, etc) and it is working very well. I don't >>> believe tapping into that at the kernel level to expose a pps signal >>> (e.g. on /dev/pps or something of the like) would be very difficult >>> at >>> all, since the low-level driver capability is already present. >>> >>> If I get some free time I'll dig around a bit and see if I can cobble >>> something up. It's of some interest to me as well since I have a GPS >>> clock here that currently talks to a serial port on an Intel-based >>> machine and being able to move that to a $35 "appliance" for NTP >>> using >>> the Adafruit setup looks sort of attractive given that the Pi plus >>> the >>> module would be under $100 all-in. >> >> Don't "cobble something up" just yet... there is "a right way" to fix >> this, which is a generic gpio-pps driver. The problem is that it >> requires support from the new INTRNG, and the rpi hasn't been converted >> to that yet. I'm checking around to see if someone has done the >> conversion for rpi and it just hasn't been reveiwed/committed yet; if >> not, I guess I'll try to do it myself. >> >> Writing the actual gpio-pps driver will be pretty quick and easy once >> we have the intrng support, I think it'll take me a couple hours. >> Any new here? Would be really nice to test this on the PI.
> Oh, so there is hope. Thanks for looking into it. > > Im not a programmer myself but im willing to help if I can. > >> Also, FYI, another option with PPS is to use a usb-serial adapter and >> feed the PPS in on the CTS or DCD pin. I tested that on rpi a few >> months ago and it worked fine. There's surpisingly little jitter even >> when the usb bus is heavily loaded with other traffic such as disk or >> network IO. >> > Yes that was going to be my plan B. Good to know that it works. > > /Peter.
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