[ntp:questions] Using Trimble TSIP under Linux

unruh unruh at invalid.ca
Sun Oct 28 22:13:59 UTC 2012

On 2012-10-28, David Taylor <david-taylor at blueyonder.co.uk.invalid> wrote:
> On 28/10/2012 08:28, Rob wrote:
>> David Taylor <david-taylor at blueyonder.co.uk.invalid> wrote:
>>> First problem with gpsd resolved, I needed a "-n" on the command-line!
>>> Next step is to see how the time a GPIO pin is triggered can be written
>>> into the SHM memory block, or whatever....
>> gpsd writes the time into the SHM block.
>> you need a serial port with data and DCD, and connect the pulse per
>> second output of the trimble to the DCD.
>> when that works you will have two SHM blocks, one with the time from
>> the serial messages and another with the time from the PPS.
> Thanks, Rob,  Herein lies a problem in that the Raspberry Pi doesn't 
> have a serial port, let alone one with a DCD line, so you need to use 
> one of the available I/O pins to raise the interrupt.  I gather that the 
> kernel supports this, but I'm then unsure how to get NTP to read the 
> time from gpsd, and the PPS from another source.  There is some work 
> described here:
>    https://github.com/davidk/adafruit-raspberrypi-linux-pps
> but I'm unsure how to make that work with my later version of Linux.

GEt pps-gpio (eg
and compile it as a module for your current kernel. Or put it into dkms
so it will be automaticaly compiled for any new kernel you install. 

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