3 Replies Latest reply on Jan 25, 2016 2:16 PM by Intel_Peter

    NTP reading GPIO PPS

    N7QNM

      I have a Trimble Thunderbolt GPS that generates a super-accurate PPS signal that I'd like to connect to a Galileo GPIO port and then to NTP for a Stratum 1 NTP server.   Has anyone done this or have any suggestions.  I did see some posts about getting PPS working in the kernel; but then nothing about the final step of interfacing that to NTP.

       

      Thanks in advance!

      Clay Jackson

        • 1. Re: NTP reading GPIO PPS
          Intel_Peter

          Hello N7NM,

           

          I personally haven't tried this but I found NTP client. There, the user AlexT provides a way to get NTP into your image, I suggest you to check it out.

          I see you already checked Re: Let's make pps_gpio work on Quark/Galileo, I believe that thread is very helpful in regards to pps. So, you could combine the information in both threads in order to continue with your project. I hope this helps.

           

          Let us know,

          Peter.

          • 2. Re: NTP reading GPIO PPS
            N7QNM

            Peter -  very good!  I think I'm about 95% of the way there.  Two more questions, if I may - the NTP PPS drivers normally access the PPS by an entry in /dev - I assume in this case that would be the same path that you used for the asserts in the pps-gpio thread.    Also, can you tell me if the GPIO inputs will tolerate TTL levels (5V) or are they 3.3V only.

             

            Will keep you posted on my progress!

             

            Thanks!

            • 3. Re: NTP reading GPIO PPS
              Intel_Peter

              I believe you are correct. The way to access the PPS is probably in /sys/class/pps/pps0/assert.

              As you can see in Galileo Datasheet under Arduino Shield Supported Features, Galileo's IO supports 3.3v or 5v. This can be set with the IOREF jumper:


              galileogen1.jpg

              Intel_Galileo2_lrg.jpg

               

              Peter.