[ntp:questions] Using Trimble TSIP under Linux

David Taylor david-taylor at blueyonder.co.uk.invalid
Sun Oct 28 14:09:21 UTC 2012

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:


but I'm unsure how to make that work with my later version of Linux.
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