[time-nuts] GPS module recommendation for Pi timing

[Hal Murray]

What do you mean by "internal TOD RTC"?

When I see "RTC", I usually think of one of those battery backed things 
running at 32 KHz.  But the Pi doesn't have one of those.  From the context, I 
think you mean what I call the system clock - what gets printed when you say 
"date".

The trick to getting decent timing from GPS on a Pi is to feed the PPS signal 
to one of the GPIO pins.  With that (and reasonable GPS reception), 1ms should 
be simple.

There are several GPS HATs available if you want to experiment before you 
build your own board.  The one from Adafruit fills the rest of the board with 
a prototyping area full of holes on a 1/10 inch grid.

For 1 ms, USB isn't out of the question.  There is at least one USB-Serial 
chip that uses the faster version of USB.  I forget the words.  Most GPS 
"mice" connect via slow USB with a polling interval of 1 ms.  The faster one 
is 8 times as fast.


-- 
These are my opinions.  I hate spam.