[time-nuts] ublox eval board

[Jeff Woolsey]

A guy at the flea market last week was selling a few ublox evaluation
kit carrying cases for five bucks, contents irrelevant.  I bought one
marked EVK-G20, which included an eval board for various ublox LTE
cellphone modules (LEON-G200 on this one).  The board itself has a
LEA-6H GNSS module. The board also has a 12V power input, a DE9S serial
port, four slide switches labelled to imply signal routing, two USB
ports, a SIM slot, headphone jack, two modem buttons (for cellphone) and
an SMA GPS antenna connector.  The kit also included a power supply and
a GPS antenna, and a headset for the cellphone module, but no cell
antenna.  I figured this might be some fun to play with.

Goals: 1)  Compare the TIMEPULSE against the PPS from my Thunderbolt. 
2)  Get Lady Heather talking to it. 3) don't spend any more $ on this.

I know the LEA-6H is not a timing module.  For $5, I can't be picky.

I got it to work using m-center and u-center on a windows-7 virtualbox
instance on a MacBook Pro.  You can also talk to it indirectly.  The
cellphone USB is FTDI, and the GPS USB is ublox API, W7 driver installed
with u-center.  You can enter AT dialer commands to the cellphone, one
of which can turn the GPS on.  About ten seconds later the PPS light
starts blinking.  Other AT commands can send UBX messages to the GNSS
and get one back; I didn't see that there were unsolicited messages.

To get the unit close enough to the TBolt to see both PPS on a scope,
the nearest computer to use for that is a PowerBook G4, for which I
found FTDI drivers and was able to turn on the GPS there.  The scope
showed in the neighborhood of 150ns difference, most of which I blame on
the long run for the TBolt antenna on the other side of the house.  Goal
#1 acheived.  53131A says about 200ns, after I figured out how to do that.

For #2 I need some way to talk to the LEA directly.  I was unable to
make the serial port do anything; the AT Command manual is very thick. 
I've been unable to find a ublox API driver for MacOS X (either 10.5.8
for PowerPC, or 10.13.4 or so for x86).  For that matter I can't find
any indication that u-center (esp. its driver) is anything other than
Windows software.

So, can Lady Heather talk to this thing with the AT+UGUBX=<UBX string>
commands and replies indirectly through the cellphone module?  Or does
anyone know more about signal routing (it talks of a UART and a
multiplexor in addition to USB) on this board?

I wonder if gpsd on my Raspberry Pi can talk to it?

-- 
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel.  -Crow on solitaire