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Re: [gpsd-users] Support request for NavSpark GPS modules!
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From: |
Gary E. Miller |
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Subject: |
Re: [gpsd-users] Support request for NavSpark GPS modules! |
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Date: |
Sun, 20 Mar 2016 14:22:37 -0700 |
Yo Sriram!
On Sun, 20 Mar 2016 10:43:30 -0500
Sriram Chadalavada <address@hidden> wrote:
> > I see in their example they mention hooking up to a USB to serial
> > converter.
> > For better timing that should likely be USB 2.0 Hi-speed. But even
> > that would be a crime to the PPS.
>
> I have used USB 2.0 with their evaluation kit. Can you provide some
> information on why the PPS NEEDS USB 3.0?
Hi-Speed is USB 2.0, so I did not mention USB 3.0. I'm not sure there
exists a USB 3.0 to serial converter. If there was I would like to
try one.
The poll rate on Full-Speed (USB 1.1) limmites the PPS accuracy to
around 1 mSec. Full-Speed (USB 2.0) gets you up to (going from memory)
about 125 uSec accuracy. That is still way worse than the few uSec
you can get from a simple RS-232 port at KPPS.
RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
address@hidden Tel:+1 541 382 8588
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