[time-nuts] RS232 / GPS interface/prototyping board

Gary E. Miller gem at rellim.com
Tue Jun 14 17:17:28 EDT 2016

Yo Attila!

First, my apologes for getting this thread started.  I misunderstood
Mark's design to have USB, when in fact it did not.  Late night brain
fart.  So any USB discussion is unrelated to his work.

On Tue, 14 Jun 2016 21:49:17 +0200
Attila Kinali <attila at kinali.ch> wrote:

> Of the devices you mentioned above, all are USB2.0, but only
> the FT2232H and the FT4232H are HS, the FT232R is FS only.
> Ie, while the FT2232H and the FT4232H support transfer speeds
> up to 12MByte/s, the FT232R supports only 3Mbyte/s
> (Rule of thumb: if the FTDI serial chip's name doesn't contain
> a H, it's most likely not a HS device)

I 100% agree with Attila.  The problem is all USB 1.1 devices are by
definition USB 2.0 Compliant.  So in a sense Herbet is right.  He is
corectly reading the marketing literature that says "USB 2.0".  

But, I refuse to say a device is USB 2.0 unless it actually does
something that is in the USB 2.0 spec and not the USB 1.1 spec.  That
usually mean High Speed instead of Full Speed.

I know that PPS over USB is laughable to a time-nut, but to me the
approximately 8x improvement in precision is very noticeable for
any host (laptop/desktop) unlucky enough to not have a real serial port

Full Speed is polled about every 1 milliSec, High speed is polled about
every 125 microSec.  A real serial port can get down to a microSec, or
better, and of course even that is laughable to most of you guys, but I'm
looking more mass market.

Once again, sorry to start the confusion...

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588
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