Driving the NTP software from a GPS w/PPS requires 1) bringing the NMEA
(typically) bytes to the computer.
Timing is not critical, USB polling at 1 msec is fine. 2) bringing the
PPS signal into the computer *is *timing critical. There's only one bit
of information.
If the PPS is brought to a
On 7/9/20 2:14 AM, Petr Titěra wrote:
Just one note. Most USB to serial chip claim USB2.0 support but they
only provide Full-Speed data transfers. That is data communication
protocol based on USB1.1 parameters with 1ms polling interval. You have
to specifically look for High-Speed (i.e
Just one note. Most USB to serial chip claim USB2.0 support but they
only provide Full-Speed data transfers. That is data communication
protocol based on USB1.1 parameters with 1ms polling interval. You have
to specifically look for High-Speed (i.e 480mbps) transfers when going
trough chip
USB:
The raw BPS are between the device and the host controller - all of
this is implemented in hardware.
USB Low-Speed, Full-Speed and Hi-Speed use a single twisted pair in
half-duplex operation. The half-duplex link multiplexes all
implemented EPs (End Points). EP0 is for link management and
I don't want to hijack Andrew's thread. Just wanted to add to Achim's
comments about jitter and offset.
USB2 devices should accept polls every 125 microseconds. [My USB knowledge
is limited.]
I have two devices. One is the Navisys GR701 which I suspect you're
familiar with; it is an
USB 1.0/Low-Speed: 1.5 Mbps
USB 1.1/Full-Speed: 12 Mbps.
USB 2.0/Hi-Speed: 480 Mbps.
USB 3.0/SuperSpeed: 5 Gbps.
USB 3.1/SuperSpeed: 10 Gbps.
This is the actual bitrate for these serial interfaces.
Bill
On Wed, Jul 8, 2020, 5:16 PM jimlux wrote:
> On 7/8/20 4:40 PM, Hal Murray wrote:
> >
> >
On 7/8/20 4:40 PM, Hal Murray wrote:
stevesommars...@gmail.com said:
My RPi4 (Raspbian Buster) has a GPS+PPS/USB. Serial->USB uses Prolific
PL2303, which supports USB 2.0
which means 1 msec polling of the PPS signal. I've been unable to poll more
frequently
As far as I know, the
