[ntp:questions] Trying to use Dimension 4 time keeper

detha detha at foad.co.za
Mon Sep 16 05:50:22 UTC 2013

On Sun, 15 Sep 2013 18:56:26 +0100, David Taylor wrote:

> On 15/09/2013 18:37, unruh wrote:
> []
>> Yes, I saw it. Not sure what the voltages are on the Sure unit -- the
>> direct output of the PPS but I think 5V which is still a bit high. I
>> guess one could put a diode in series with the line to bring it down to
>> 3.3V.
> I would recommend using a restive divider - perhaps 10K and 4.7K to start
> with - and monitoring the voltage into the Raspberry Pi.  Using resistors
> provides a current limit, and allows the voltage to get down to zero.  If
> the voltage is well below 3.3V, the upper 4.7 K resistor could be reduced.
>  Best to ask on one of the Raspberry Pi support groups as someone has
> likely already done the measurements.

might be of interest. For converting serial signals it works fine,
for PPS where one worries about being 100ns off maybe not so much.

More information about the questions mailing list