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

David Taylor david-taylor at blueyonder.co.uk.invalid
Sun Sep 15 17:56:26 UTC 2013

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.

But the Sure unit is so big, physically, that I would still prefer to 
use the Adafruit instead.
Web: http://www.satsignal.eu

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